I - Inviting you to team up/join their organization of heroes:
Dabi would have listened closely to what you thought about Stain, and whether or not you were a hero or villain before he asks you to join the League of Villains. He knows Shigaraki would let you join so long as you're useful, which is another thing he scouts out first. He wouldn't necessarily befriend you first, but he would assure you're the type of person who fits in with his people before extending the offer out.