@Soda_can he did (multiple times), but Chase refused.

Spoiler!
Chase doesn't like ruts 'cause he's afraid of losing control and hurting someone, after he did it with Josh (he doesn't know it was Josh yet) for the first time (he was a virgin before), he didn't hate it but he's memories were blurry and he's really scared 'cause he thinks that he may have 🍇 the omega (he wasn't in his right mind), that's why he's afraid of ruts and hates pheromones, he doesn't watch to take advantage of someone else or be taken advantage by someone else. He's a softy, he's emotional, and sensitive, but others say that that's weird, so he distance himself and is mean to everyone because he's scared, he can't trust others because no one has ever really loved him, accepted him, and cared about him (but Josh will help him) TT

"My one and only" T-T