I like [name_u]Sorrel[/name_u]! It’s pretty and unique
Here’s some ideas for the protagonist:
Jetterson instead of the ever common [name_m]Jefferson[/name_m]. Nickname Jettrey or [name_m]Jett[/name_m]/[name_u]Jet[/name_u]
[name_m]Renaldo[/name_m] nickname [name_u]Ren[/name_u]
[name_m]Raymond[/name_m] nn [name_u]Ray[/name_u]
[name_u]Everest[/name_u] nn Rest, [name_u]Ever[/name_u], [name_f]Eve[/name_f] (I know it’s a girl’s name but I kinda like it for a guy)
[name_f]Shadow[/name_f]
Thalen
[name_u]Hunter[/name_u]
[name_u]Rain[/name_u]
A nickname doesn’t have to be because of a given name. Maybe [name_m]Steve[/name_m]'s friends call him [name_m]Trip[/name_m] because he’s clumsy. Maybe [name_m]Matthew[/name_m] is in a secret club where they pick code-names so he’s called [name_u]Storm[/name_u]. Maybe the government gives [name_m]John[/name_m] the name [name_u]Harper[/name_u] when he turns eighteen because every eighteen year-old gets a new name by law. Be creative. Have fun.
[name_f]Hope[/name_f] I helped 
Good luck!