He nearly chokes at the question and, for the longest time, all he can do is stare at Stiles. Talking about his feelings isn’t something he wants to do and his brain is working overtime, trying to keep his mouth from making the stupid fucking sounds to form the stupid fucking words to put his stupid fucking feelings out in the open.
"You’re… " His jaw clenches and his fingers tighten into the hem of his shirt and, goddamn, he wishes the world would open up and swallow him fucking whole.
But the harder he tries to keep it from happening, the more of himself he’s spilling out until he’s sure there can’t possibly be anything left inside of him.
"You’re e-everything. To me. You’re the first thought I have in the morning and the last thought I have before I go to sleep and every single fucking thought in between.” There goes his guts.
"You’re the reason I still fight. The reason that I even get myself out of the fucking bed in the morning. You’re all I fucking have left. I tried… So fucking hard. To keep you at a distance because holy shit you annoy the ever living fuck out of me. Annoy. Present tense. But you’re like. You’re persistent as shit and you’ve managed to burrow your way into what’s left of me and you’re the only fucking thing keeping me together anymore. You are the fucking glue that’s keeping me standing and I don’t think… I know I couldn’t. I wouldn’t. Survive… I couldn’t make it through a fucking day without you.” His stomach, lungs, his blood are pooling around him.
All that’s left inside of him is his heart; he’d offer to give that to Stiles too, but it’s so broken and irreparably damaged and there’s not enough King’s horses and King’s men to put it back together again.
And Isaac knows he deserves so much more than the wolf could ever give him.
He's quiet through the whole confession, his heart going rabbit fast as he listens. Part of it is from the left over adrenaline in asking at all. He'd expected... well he wasn't sure what he'd expected but not... not this. Now that he's hearing it though, and the full impact of what Isaac is telling him hits, he realizes it's something he's been desperately needing.
When the beta falls silent again he's slipping off his chair, sliding over to him and winding up on his knees in front of Isaac, pushing him to sit on Stiles' bed and looking up at him with wide eyes. "I- Oh my god." He can't maintain the eye contact, has to bury his face against Isaac's chest, holding him tight by the waist.
"I don't... I haven't had anyone like... here for me like you are. Like, I know I have people in certain ways but it's not the same with you. You're- you're different, and special and- and just as important to me as Scott or my dad and I'd go freaking crazy if anything happened to you..."
He swallows hard, and it hurts to confess, feels like he's carving out his chest, but he took advantage of the honesty thing, and there is no way he can do anything less after that. "It's like I hit that point of starving where you don't even feel hungry anymore and then there was you with your ugly fucking scarves, and shitty attitude, and that damn smirk that I'm never sure if it makes me want to shred every scarf you own or kiss you stupid, and there for me every time I text or call at some unholy hour even when all I needed was to ramble at somebody because my brain was too full. And it's like, oh fuck I need that, I literally need that, and there isn't anyone else at all that can- can be that, no one else I need the way I need to eat to stay alive."
"I think about you all damn day, 'oh I need to tell Isaac about this, it'll make him laugh', or 'this is a great song I need to share it with him', or 'I bet this will piss him right the fuck off I must find him immediately' because yeah, I'm an asshole, but so are you and fucking hell if that doesn't make me lo-" He stubbles on the last word, holding Isaac tight enough that a normal human would probably have some serious worries about breathing.
"If that doesn't kinda make me love you even more." He mumbles into the werewolf's shirt. "I kinda don't like you as much during those moments you're an asshole. Sometimes I think I don't like you much at all because ugh you're a fucking annoying shit. But I do still love you. I love all the pieces of you. The boiling anger, the raw hurt, the bone deep stupidity of your wardrobe, your smile like fucking sunshine and your dumb curly hair. All of it."
So now it's his heart on the line. It feels like he's cut it out and put it in a glass box, and if it's rejected now the box will fall and shatter and he'll be left with nothing but painful glass shards and a shredded lump of bloody meat. And fuck he's so scared that Isaac is going to chose now to say this is getting to be more than he'd signed up for or something, or to realize that he really should be with someone who's nicer, kinder, gentler than Stiles is. Someone the exact opposite of Stiles.