Harry had never understood just how much danger he was about to face. Sure, he knew of the Unforgivable Curses and the horrid deaths they could easily cause, but he never realized just how dangerous going to war in the Wizarding World could be. There are many ways for a Wizard to kill a person— many more curses and poisons that can be conjured and severely more deaths that can be caused with just a touch of magic.
In muggle Primary School Harry had learnt of the muggle wars such as the Great War and the Second World War, and so he knew of the desolation, the trench wars and the arms race, and the violence that exceeded anything he had ever learnt about at Hogwarts. However, he never thought that Wizard's would fight in this violent fashion as well. It had seemed to be something that any Wizard, Muggleborn or Pure Blood, would never stoop to doing. But war can make civil people do very inhuman things.
Harry watched in devastation as daggers were thrown into Snape's arms and legs by a magical force. There was little blood, for Snape did not bother to remove any of the weapons from his body as he ran with all his might toward a small trench Harry had made earlier during the battle.
Hermione had been hit with a foreign spell that rendered her legs immobile, and she needed time in order to reverse the spell, so Harry did the best thing he could think up. He carried her back from the front line and spelled a ditch into the ground, giving her safety from the battle and time to work and heal. After a short interlude, Hermione had removed the spell, but others were becoming wounded and in need of momentary shelter. Soon, the ditch had become a trench and those that were wounded traveled there for time, shelter, and a chance to Apparate to the large trench about a half-mile away, where Madam Pomfrey and her helpers were stationed. It was just as though they were fighting in the Great War instead of this war against the Dark Lord.
Harry was shocked out of his intent staring at his wounded Professor as a Stupefy hit Harry squarely in the chest. He fell to the ground from the force of the spell, but was not affected by it in any other way, for Snape and Harry and concocted a spell to protect their major organs from any and all spells cast with at least three feet between the caster and the target. It covered the whole torso, including the neck and head, from all sides. Their limbs were not protected at all because the stretching of the spell over the entire body would cause the spell to be easily broken, and the spell was hard enough to cast as it is.
Harry did not bother standing as he cast three Stupefy in quick succession, knocking the Death Eater down and most likely rendering him unconscious. As Harry stood he cast four more Stupefy at Snape's attacker, Bellatrix, and managed to catch a glimpse of Snape as the wounded man slid into the trench and out of sight.
The battle field was still active, and Harry knew others would be sent after him if he stood out in the open. So he told Hermione to watch his back as he made for the trench, seeing as Ron— who was standing just a few feet away— was currently engrossed in duel, which was quickly turning into a fistfight, against Rabastan Lestrange. Harry's trek to the trench was uneventful thanks to Hermione, and he slithered down to sit across from the now blood-covered Snape.
"Need help?" Harry asked in a deathly quiet whisper, staring at the point where his and Snape's feet touched because of the trench's small size. Snape grunted in response, shifting his wounded legs so that they were in between Harry's bent legs. Snape's feet pressed somewhat against Harry's crotch and inner thigh, but Harry ignored his growing feelings and focused intently on removing the daggers from Snape's legs and healing the puncture wounds they left behind.
As he steadily worked on in silence a memory, in which Harry meet Snape in one of the more run-down alleys near Diagon Alley, emerged into Harry's conscious thoughts. Harry had been searching for ways to create new spells and potions when Snape appeared out of nowhere. He had looked intently at Harry, not smirking or scowling at him but simply staring straight-faced at his enemy, before he turned with a flourish of his big black cloak and started to run down the path. Harry had jerked into action, running after Snape in a determined rush, only to come to a screeching halt as Snape stood at a dead-end with his back to the brick wall and his wand hand outstretched.
"I am on your side," Snape said to Harry, lifting up with his left hand a small Pensieve and, before Harry could react, thrusting Harry face first into the bowl filled with Snape's memories. Inside the Pensieve Harry had seen all he needed to see to know Snape spoke the truth, as well as enough torturous memories of Snape's to last several lifetimes. Harry had seen Snape talking with Dumbledore as he discovered that he must kill the old man— his mentor— and Harry had watched as Snape vowed with Dumbledore to kill him when the time comes, and then vowed with Narcissa to protect her son and do Draco's deed if he could not. Harry had looked on, despite his wrenching gut, and watched as Snape killed Dumbledore, as Snape mourned Dumbledore, as Snape tortured himself with starvation and self-induced bruising over Dumbledore's death. Then Harry watched as Snape regained sanity, as Snape remembered the second part of his vow with Dumbledore, the portion of the vow that consisted solely of the order; "Protect Harry."
After his trip in the Pensieve, Harry and Snape joined forces occasionally— when Snape's role as Death Eater under Voldemort permitted— and created spells and potions to use during the war. They created many useful things, but the greatest spell they made was Protector, a conveniently named though hard to perform spell that protected whomever the caster chose to protect. It is most effective if performed by one person to protect another, for the magic is weaker when the caster's intent is to save their own skin.
Snape worked as a double agent until the previous battle, in which Harry was surrounded by five Death Eater's, and the only person who could get through and save him without dying in the process was Snape. In all truth, Harry was very glad Snape was on his side.
Harry grunted softly as one of the daggers stayed stubbornly lodged within Snape's calf. Harry had thought better of pulling the dagger out by hand, for the blade seemed to be very close, if not touching, the bone in Snape's leg. However, magic proved difficult for the very same reason. Each time Harry started to remove the dagger, it slid against something, causing Snape's leg to twitch involuntarily and the spell to break.
"Go on and yank it out," Snape said, and Harry brought his face up to peer at Snape. He looked like Professor Snape stirring a potion, for he starred with such an intent focus at his arm; a focus that Harry could only recall having seen on Snape's face when he worked with potions.
"Professor," Harry whispered to himself, but Snape heard the minute sound all the same.
"Beg pardon?" Snape asked in his deep, thick voice that always gave Harry chills. Harry coughed into his forearm and said nothing as he wrenched the dagger from Snape's leg. Blood gushed forth, pouring over Snape's leg and pooling on the ground around them, and both Wizard's starred in shock for a split second.
"Fuck," Harry said with his eyes wide open and staring at the blood as he healed Snape's leg in a rush. Harry managed to replace some of the blood into Snape's body, but unfortunately it was not enough. Snape was panting heavily with his arms at his sides, his face a ghostly pale tinged with green. Harry gasped and slipped across the muddied ground to Snape's side, propping Snape's limp body up while he cast a spell to be rid of the bloody mess before gently laying Snape down across his lap.
Harry pet Snape's head soothingly as he cast a strong healing spell, which forced the daggers out as well as healing the wounds the left. Soon Snape stopped panting as his health was regained. With shaky arms Snape lifted himself up, shifting so that he sat in his original spot against the trench's dirt wall.
"You should have done that earlier," Snape said with dark humor, a smirk gracing his now considerably less pale face. Harry laughed softly, turning to stare again at the point in which his and Snape's feet touched, though now they were side-by-side.
"I didn't know I could do that," Harry confessed to their feet, "until now, of course." Harry felt, rather than saw, Snape nod his head, his shoulder shifting slightly against Harry's. Continuing to stare at their feet, Harry felt Snape move again, shifting his whole body so that he could look at Harry's face clearly and without straining his neck.
"It's hard to see you down there," Snape said calmly, and Harry peered sideways at him, finding no hint of humor visible in Snape's face save for a slight glimmer in his eye. The glimmer reminded Harry of Dumbledore and his twinkle. Harry always felt like crying when he thought of Dumbledore, but this time was strangely different. This time Harry felt happy to remember Dumbledore; to remember one of his good qualities, and to have found this quality in Snape.
"I'm good at disappearing," replied Harry as he smiled, mirroring Snape's previous shift in position so that they were once again sitting across from each other.
"So I've seen," Snape said, the glimmer in his eyes seeping into his voice, causing it to lilt with good humor, "Countless times, in fact." Harry's smile broadened, his cheeks turning pink, as he finally looked Snape in the eye. They gazed at one another for a time, the thought of the battle lost from their minds.
Luna Lovegood appearing in the trench with a thud, her left arm slightly mangled and bleeding, was what finally drew the two Wizard's back into reality.
"Luna!" said Harry as he rushed to begin healing her wounded arm. It was an easy mend, thankfully, and the three of them were back on the battle field in less than a minute. Luna exited first with a helpful boost from Harry, who scrambled out after her in order to help Snape up. Luna stood guard on Harry's backside as he gave Snape his hand for leverage, and after a short moment was taken to check the Protector spells present on all three of them, they stormed the battle front once more.