Best Friends
Trunks and Goten are best friends in the future episodes. They fight along side each other and train with each other. They end up fusing together and becoming Gotenks(shown below).Goten is like his father, Goku, as a child and when he is not fighting he neglects his training for girls.
Click on the pic towards the left to transfer to my friend's website, which has more pics and GIFs of Goten and Trunks!