L.!.
I agree with previous posters that Corbyn with the y seems feminine and prefer it with an i for a boy's name.
I think if you chose Brecken, he will probably be called Breck by most friends... And that makes me think of women's hair shampoo.
I like Holden; I like Corbin... Don't like both together. I like James Brecken. Like Holden James and Corbin James.
Good luck, the name game is hard! Sometimes you have to put it on hold for a few days and then revisit it.