Can i breed out natural fighting behavior in Aseels and other game chickens.

No. Small numbers wont help anything, males need to be the only male in a flock and unrelated hens are often too quarrelsome to be kept together. In the case of hens, that is with the exception of a free-ranged scenario, which often works out. With almost any of the bloodlines that you'll be able to get your hands on, related hens will be perfectly fine together, whether 2 or 100. Raised under a silkie or any other chicken will not affect anything to your liking either, as their indomitable nature is wholly genetic. BUT....if the birds you started out with were already contaminated with non-game blood somewhere along the line...then yes. Which, considering that "line" I mention goes back thousands of years, almost all of them have some questionable blood in their history that can show up unexpectedly and be used to accomplish what you desire. If they were pretty good bloodlines, though, it will be a very, very costly, long, hard road. And regardless of being a good or bad bloodline, after many generations, yes, through your selection of timid/submissive individuals you would eventually have devolved a line that are no longer preserved game chickens.

Why you are thinking about doing what you mention, I don't know. There are oriental, hard-feather "gamefowl" breeds that will not be so troublesome as the preserved game ones. For example, possibly many of the bantam lines of Asil and shamo, for sure Malay and bantam Malay, (and Cornish, while not technically in this group, look very similar you may like them.) Also the saipan junglefowl will probably be a safe option. And even many of the shamo you find at hatcheries will be fine, although that last suggestion may be risky.

Ok thanks