Although there are individuals who turn out bad like in any breed of animal, I definitely would not say aggressiveness in males is a breed trait for the Dominique. Because most breeders do want to show their birds they would not want a mean bird nor would a mean rooster be a good breeder as he would terrorize the hens. I would give him a little longer to sort out hormones, maybe even handling him more might help tone him down. My extra nice older rooster gets cocky with my son who is 8 and likes to tease him, but I can walk right up to him, pick him up, handle him, trim spurs, give baths, put him on a tiny kitchen scale for weighing, etc. without a single flap out of him. I do not handle them unless necessary, so they must be "pret a porte" whenever something needs done. My youngest boy "Wyatt" likes to jump up to see what's in my pocket if I lean over.
On Marans, mine were from Melanie Nealeigh in Greenville OH. She occasionally sells in the warmer months on craigslist. She is always winning BOS at the county fair. Her stock I believe is from Wade Jean lines, but that is all I know. I have been at her place a few times, and she is always carrying around one of her big ole Marans roosters and he just lays there in her arm like a lapdog. Our pet hen lets my 4 year old carry her around.