Inspired by that scene in 5x14 "Crush" where poor Willow's downing painkillers at the Bronze to deal with her headaches. She mentions those headaches and nosebleeds enough times later on that it's clear they never went away. She's got an addictive personality and by Season 6 she's always looking for an easy way out—so I think a little reliance on medication isn't too far of a stretch for her.
This takes place between seasons 5 and 6, while Buffy's dead and Willow and Tara are living in Buffy's house taking care of Dawn and fighting baddies with the gang.
Headaches and Nosebleeds by Heckate
It was another night without Buffy, and each of those seemed to pile exhaustion onto their shoulders, for the evils they fought did not lessen just because the Slayer was gone.
Willow stretched and groaned as she slid into Joyce's former bedroom that she shared with Tara, relieved that she could show her weakness around her girlfriend. Her friends, of course, counted on her strength; she was the "big gun", after all. And she'd spent the night casting fireballs and floating stakes just to keep them alive.
"Here, sweetie," said Tara, her sweet smile contagious and putting one on Willow's face as well. Willow looked down at what Tara was handing her—a tissue. She furrowed her brow for a moment, and then touched her upper lip, bringing her hand away to see the blood pooling there on her finger. Her smile became a frown, and she took the tissue with a nod of thanks, wiping the blood from her nose and stumbling to the bathroom to take care of it without staining the carpet in blood.
Tara sighed, her concern ever-growing. Concern about Willow's inappropriate use of her powers, her sheer amount of power, and the effect her powers had on her body. Tara never experienced the physical effects of magic at the intensity and frequency that Willow did. Then again, Tara did not do spells as strong or as often as Willow did, either. She couldn't if she tried; she didn't have that kind of power.
Willow emerged from the bathroom with a glass of water and Tara went in after her. She peeked into the trashcan and saw Willow's discarded tissue positively soaked with blood. She bit her lip, idly wondering about the long-term effects of too many nosebleeds. What was it—every other day, now? Willow had been using more and more magic to keep them all safe since Buffy died, and every day it seemed to take a bigger toll on her.
Tara washed her face and came back into the bedroom. She looked at Willow, who was feeling blindly around her nightstand. Her eyes were squinted, all but shut, the bright light of the room apparently aggravating her headache. Tara quickly turned off the overhead light and turned on the dimmer bedside lamp instead.
"Better?" she asked.
Willow nodded gratefully, blinking her eyes open. She grabbed a pill bottle from inside the nightstand and poured several tablets into her hand.
A prescription pill bottle, Tara realized, and she wondered if Willow had gone to the doctor without telling her, "Where'd you get those?"
Willow looked up at her, "Huh?" She glanced down at the pills in her hand, "Oh, from the medicine cabinet. Headaches."
Tara marched over and grabbed the bottle, though Willow didn't seem like she was trying to hide it. Tara turned the orange container over in her hands—she knew enough about medications from taking care of her mother, and more from her deep knowledge of medicinal herbs, "Willow, this is really strong stuff. Can't you take an Aspirin?"
"Aspirin doesn't work anymore," said Willow, trying to grab the bottle back without dropping the pills already in her hand. Tara was using her 'I-Don't-Approve' voice, and Willow was becoming self-conscious.
Tara looked at the bottle more closely, holding it away from Willow. In bold black letters she read the name JOYCE SUMMERS, "Willow, these were for Buffy's mom."
"Well she's not…" Willow tried to word it in the kindest way possible, "...She doesn't really… need them anymore…"
"But Will, she had brain surgery. These are for brain surgery headaches." Tara knew her panic was coming out like anger, and that only made her panic more, "How long have you been taking these?"
"I don't know," said Willow, "a few weeks."
Tara looked at Willow's hands, which were nervously fiddling with five of the tablets. "Goddess, Willow. You can't take that many!"
Willow huffed in offense, "Why not?"
"You just… can't!"
"There's a lot of things you think I 'can't' do, Tare. Can't use too much magic, can't get too powerful, can't bring Buffy back. But you've never have real good reasons." Willow regretted the jab as soon as she'd said it, but she was too worked up to apologize.
Tara frowned, sensing the fight and willing it to go away, "Will, if you're in pain, your body is trying to tell you that you're doing something wrong."
Of course it came back to her damn magic use! Willow clenched her fists, hating how angry she got nowadays. She took a deep breath—if she could hide her weakness from her friends, she could hide her anger from Tara, too. "Maybe in ye olde traditional wicca times," she joked, "but nowadays we have the miracle of modern medical science!" She held up a pill and grinned at it. "Try saying that five times fast."
"It's unnatural," said Tara.
"Why?" said Willow, "It's just the same as herbs and stuff, just with a pinch of science."
"It's not healthy, Will,"
"Tara, I'm not a junkie in some After School Special. It's not about a high or anything, I just need to get rid of the pain so I can focus and sleep. So that I can keep fighting the good fight and helping you guys. I used to take normal stuff but it just doesn't work anymore, okay? I used to take less. This doesn't happen to you, not like it happens to me. You don't get it."
It doesn't happen to me, Tara felt herself almost say, because I respect the rules. But she knew that would really get them fighting so instead she went with something gentler. "Willow…" Tara swished the question around in her mouth for a moment, "How long have you been taking painkillers? For your headaches?"
"Why does it matter?" said Willow.
"It was that teleportation spell, wasn't it?" said Tara, "For Glory? You went through a bottle of Aspirin that week."
"Look Tare, I did magic for more than a year before I even met you, okay?"
That was answer enough for Tara. She held out her hand, "Sweetie, will you give me the pills?"
"What?" said Willow, moving her hand away from Tara, "No."
"What if I make some calming tea instead? I'll use Willow Bark."
"Tara, it won't work," said Willow, "Please, I wouldn't take this stuff if I didn't need it."
"I can brew something to help you sleep."
"I can't sleep when it's like this. I see these flashes behind my eyes and my ears are all ring-y. It's like there's a little construction crew in my brain and they all wanna get paid overtime."
"Willow, you're gonna hurt yourself." Tara thought for a moment, "You're already hurting yourself."
"Isn't it worth it?" pleaded Willow, "Every day I'm the 'big gun', and I have to fight all the bad guys, and use all this power. Plus I have to lead the group, and I have to keep the Buffy Bot up and running. Isn't all that worth a few headaches and nosebleeds? And don't I deserve to make the pain go away a little?" She glanced at the pill bottle still in Tara's hands, "It's not forever. I'm gonna run out of those eventually. I'll… you can find me some real strong herbs, right? To make the headaches stop, and it will be all natural and green."
Tara sighed. It didn't work like that—magickal herbs weren't meant to cover up problems on a long-term scale, especially problems caused by magicks themselves. But it seemed like Willow was trying to end the fight. Tara looked into Willow's eyes and saw her squint even at the dim light of the bedside lamp. A tiny bit of blood started to leak again from her nose. What kind of girlfriend would Tara be if she locked Willow in a fight while she was exhausted and in so much pain? They'd talk about it some other time, "Fine."
Willow's shaky hand brought the pills to her mouth and another brought the glass of water. She sighed with relief and collapsed into bed with a groan, still fully clothed. Tara tucked her in and brought a tissue to Willow's face to wipe up the new, though smaller, nosebleed.
Willow fell asleep quickly—probably because of the pills. Tara sighed a long sigh, wondering honestly if this would ever end. All of it—they couldn't go on like this. Willow was falling apart, and so was she.
And it went against everything that Tara believed in, but she almost started to wish that there was a way they could bring Buffy back. To lift the weight from Willow's shoulders, so that she wasn't forced to use so much magic all the time, so she wasn't hurting herself every night and so that things could go back to the way they were.
A glance at Willow made Tara wonder if Buffy coming back would really change anything, though. After all, everything that frightened Tara about Willow had already begun long before they put Buffy in the ground.
I haven't written a Buffy fic since I was a teenager! If you liked it, let me know and maybe I'll write some more.