Keep him and enjoy him! I keep Japanese Bantams as pets and I keep them mainly for the roosters are they are so colourful and beautiful with long tails and bright red combs.
I now have 4 roosters and 8 hens. Before I had 7 roosters until I re homes some. They all get along fine even through some were added later.
They will eat the same food as the hens no problem and can be left in with them - especially as you only have one. Sometimes a group will mate with the hens too much and cause them to loose feathers. One should not be a problem.
They all differ in their personalities. 2 of mine are cuddly tame and love to be picked up and petted, falling asleep. One is a 'normal' rooster and he just struts about looking pretty and will feed from my hand, but is too frightened to let me pick him up. The last one is the nasty one. He is great apart from if I try to pick him up he will bite me several times hard! As he is so small its not a problem and its quite funny. I remember he even used to bite my hand in his brooder when all the other chicks would run away! He is nice to all the other roosters and chickens though.
I love watching them all free ranging in the garden, flapping wings and crowing. Lovely to see.
I also get the advantage of fertile eggs, so I hatch out a few chicks sometimes which is also fun.
