Chick Markings scream Sumatra to me as well.Black sumatra. Don't believe when people tell you there are mean, mine are super friendly! But same as any chicken, handle him/her as much as possible.
& I concur, Sumatras are generally a very sweet breed! I have a hen we call "tap dancer" who is constantly tapping her feet all happy like and insists on making sure she lays her eggs right under my feet whenever possible. Wasn't excessively handled as chicks, they're just mellow lil talkers by nature