Birds of a Feather (Winged Deku x Hawks)

Au base info:

Izuku's quirk is called 'Bird of Paradise'. He has shimmery green wings with hints of  blue and gold. He can make his wings appear and disappear at will with just a small burst of green light. He is also able to turn into a blue green bird of paradise. Due to this quirk he also has some bird like animalistic instincts. During the first week of spring his body temp will raise and he will become moody. He will also clutch and nest. (Will make a nest out of what ever is around him. He also has an egg pillow that he becomes very parental/ protective towards.) He will also be much more easily distracted and fidget more during the reminder of spring after the first week. Also he has a mating dance that is prompted by his quirk. He can do it at any time but, the closer it is to spring the more the dance is controlled by his quirk. ( This dance also serves as the base for a mating bond.) Izuku is also naturally drawn to other people with nature/ animal based quirks. 

During the first week of spring Hawks will get sick. Its like a fervor, some springs it is not so bad, some springs it gets worse. After the first week of spring he goes back to normal. Although his quirk is mostly like a hawk it is also partially like an eagle, and like an eagle he forms a life time mating bond. Hawks gets very excited when he sees/ meets others with avian based quirks. 

Tokoyami accidentally killed his younger sister with his quirk when he first discovered it. He felt horrible about it. His family never blamed hi for it but, when they had children in the future they never allowed him near them. Due to that he felt excluded from his family and would spend a lot of time alone at a near by park. During this time he became very close to dark shadow. (Dark shadow goes by them/her pronouns and is bound to Tokoyami as his mate.) It is when Tokoyami is 6 that he and Dark Shadow meet Izuku in the park. Izuku declares himself as their brother and they all become close, spending lots of time together. Even having sleep overs and hang outs at each others houses.