Sirius' Animagus form wasn't always a dog.
In fact, when he first learned to become an Animagus, he was quite the opposite; his Animagus took the form of a cougar, powerful, lithe, and strong. Strong enough to keep a fully grown werewolf at bay.
That, however, was before "the fall."
The Gryffindor fifth year male dormitory was completely silent at dawn; as the night before had been the full moon, most of the boys were asleep, trying to rest off the long night.
Most, but not all.
Sirius Black was very much awake, although he would rather be asleep. He had long ago wiped the sleep from his eyes, and was now alternating between watching the sun rise and watching his friend's chest fall.
A habit he had regrettably fallen into, and one he couldn't seem to shake.
He was perfectly aware that Remus couldn't and wouldn't ever be with him. There were too many reasons he couldn't reason away, too much logic he couldn't beat, too many forces working against him he couldn't try to fight.
And yet he couldn't escape the tight feeling in his chest every time Remus walked toward him. The smile that crossed his face every time Remus sat beside him. The loss of breath every time Remus' skin even accidentally grazed his own.
He frowned. If James ever heard me thinking like this…
If James ever heard me thinking like this, he reasoned, he probably wouldn't be surprised. It's painfully obvious to them. To everyone. Except Remus.
He brought his knees up to his chest and wrapped his arms around them. He laid his head back against the wall. He hesitated, then let his eyes flickered to and rested on Remus' sleeping form.
Or what he thought was Remus' sleeping form.
"Sirius?" asked the sleeping form. The boy sat up and trained his eyes on him. "Why are you up so early?"
"Um." He found it incredibly hard to lie this early in the morning. "I was watching the sunrise." It wasn't really a lie…
"When was the last time you watched a sunrise? Beside this morning," he clarified.
"Yesterday morning," answered Sirius, and again it wasn't a lie.
Remus frowned. "Are you having trouble sleeping?"
"Yeah." Another not-lie.
Sirius blinked and looked away. He couldn't half-lie himself out of this, not before breakfast. "It's not that I'm having problems sleeping."
"Okay…" Remus sat on the edge of the seat when Sirius scooted his feet back. "So what's your real problem?"
"I can't lie with you, can I?" asked Sirius, a wry smile temporarily appearing on his face.
"You really can't," Remus answered.
The smile was gone, and Sirius frowned again, the lines etching deeply into his face.
"Do you want the truth?" he asked, looking his friend in the eye.
"There's no point in lying, is there?"
Sirius saw his point but wanted desperately to avoid it. To stall, he glanced out the window. "The sunrise is always more beautiful after the full moon."
"How long have you been watching the sunrise?" asked Remus.
"A few months, maybe more." He shrugged. "It's not a big deal."
Instead of trying to argue with him, Remus continued on the same path. "Why the sunrise?"
"It's like a beginning. A mini-creation every day. No one ever sees it because they aren't willing to get up and find the time, you know? But if you catch it…"
Remus nodded and watched outside for a moment. "And you've always felt like this?"
"At first, I watched it because I couldn't sleep and there wasn't anything better to do, you know? But then I watched it, really watched it. It's beautiful."
Remus frowned, catching on. "Who is it, Padfoot?"
Sirius' eyes widened momentarily, then relaxed, resembling defeat. "I should have known you would have figured it out."
"So?" asked Remus. "Who is it?"
"The truth?" asked Sirius, his voice barely above a whisper.
"The truth," Remus confirmed.
Remus was genuinely surprised, scooting away from Sirius, who frowned and tried to hide the pain already appearing on his face. "You…can't."
"Can't I?" questioned Sirius, looking out the window again. "Because I'm fairly certain I do."
"It's me, Sirius," muttered Remus, trying to make sense of the situation. "I'm a werewolf. Werewolves are dangerous, uncontrollable beasts, Siri…you can't."
"I can control you," answered Sirius, passion leaking into his voice. "You're a werewolf once a month, and I can control you. You've seen me control you. I swear…"
"Sirius, please," whispered Remus.
"No," answered Sirius. "You don't understand."
"You're attracted to me too, aren't you?" he asked, switching gears. "You don't want to admit it, but you are."
"It's…not that," finished Remus lamely.
"Why not?" demanded Sirius. "You like me! I…I love you!"
Both boys were shocked by his words, and a temporary pause let Remus consider his response. "It's not that I'm not attracted to you."
"Then what is it?" asked Sirius, quieter now. "What could stop us?"
"You come back to the dorm with a different girl every other night," muttered Remus. "There's no possible way—"
"That I could love you?" asked Sirius, a harsh edge to his tone. "Haven't you noticed? I haven't slept with a girl in months, and even before then it was never them I was seeing."
Remus looked away, knowing, and fearing, what he would say next.
"It was you."
"Sirius, I'm sorry." He couldn't bear to hear any more. "But I can't."
Sirius knew it was the end of the conversation, but couldn't make himself move. In the end, Remus moved and left him in silence.
"He didn't come with us during transformations for three months after that," Remus said, glancing at the boy in front of him. "And when he came back…"
"He was the dog."
Remus nodded and met Harry's eyes. "I never meant to hurt him. I thought…"
Harry suddenly removed his glasses and wiped them, as though they would help him understand better. "Why…why are you telling me this?"
"You deserve to know," answered Remus, looking away. "We were your age. I didn't want him to be tied to me. When we were at school, we were in this perfect little bubble, you know? But when we were in the real world…it would never have worked." An awkward silence filled the room, and Remus had to wipe a tear from his eye. "I never expected him to die before…before I could right the situation."
Harry nodded briefly, looking away. "I don't think he ever got over you."
"He didn't?" asked Remus.
"He didn't. He was so depressed…"
"He guarded himself around me, after that," he answered. "He didn't want to let me in anymore." He frowned. "You're probably right. I don't want to admit it, but you are."
"Did you?" asked Harry.
It was at times like these that Harry reminded Remus of James more than anything else. "Would you hate me if I said yes?"
"No," answered Harry.
Remus nodded and looked away. "Then yes." He looked down at his empty glass, then Harry's. "I think we need something stronger."
He Summoned a glass of Sirius' firewhisky from the cabinet and filled both their glasses.
Harry raised his glass. "To Sirius."
Remus nodded, but didn't meet the boy's eyes. "To Sirius."
Sirius' Animagus form was not always a dog. Sitting there, Remus realized that no matter what he had done, it would not have remained as the cougar, in the end. Either way, Sirius was destined to become a dog, a darker, more accepted version of Remus himself.
The firewhisky seared his throat, and he choked back the tears with it.