I think [name_m]Rio[/name_m] and [name_m]Asa[/name_m] would work really well with brothers, and i agree that [name_m]Cruz[/name_m] and [name_m]Felix[/name_m] also totally fit the same vibe and any combinations of these names as brothers work great.
[name_f][/name_f]More that i think fit:
[name_f][/name_f][name_m]Leo[/name_m]
[name_f][/name_f][name_m]Luca[/name_m]
[name_f][/name_f][name_m]Nico[/name_m]
[name_f][/name_f][name_m]Enzo[/name_m]
[name_f][/name_f][name_m]Ezra[/name_m]
[name_f][/name_f][name_m]Otto[/name_m]
[name_f][/name_f][name_m]Kai[/name_m]
[name_f][/name_f][name_m]Marlo[/name_m]
[name_f][/name_f][name_m]Nilo[/name_m]
[name_f][/name_f][name_m]Milo[/name_m]
[name_f][/name_f][name_m]Noel[/name_m]
[name_f][/name_f][name_m]Axel[/name_m]
[name_f][/name_f][name_m]Jude[/name_m]
[name_f][/name_f][name_m]Rafe[/name_m]
[name_f][/name_f][name_m]Theo[/name_m] / [name_m]Teo[/name_m]
[name_f][/name_f][name_m]Seth[/name_m]
[name_f][/name_f][name_m]Amos[/name_m]
[name_f][/name_f][name_m]Rex[/name_m]
[name_f][/name_f][name_m]Aris[/name_m]