We have our almost 2 yr old brindle male boxer, and also a male 12 yr old mix of everything dog. They get along for the most part, but the older one requires a lot of his "me" time where he likes to be alone.
My brother's house has Zoe, Titan's sister who is also almost 2 (they were from same litter) and an 8 yr old beagle mix female. They get along usually but dominance is a problem occasionally. At the same time they also has a 10 yr old male brindle boxer and a 2 yr old male terrier, both of whom have left us now :(