Even though it's Vilkas now who mostly perpetuates the strain in their relationship, Crescent was the one who initially started feeling unable to relate to his brother, back when Vilkas lived with Beijeye. Vilkas hadn't forgotten what it was like living with their family and that the two of them where basically in it together. But Crescent has never really known any other life, he can't get his head around how Vilkas is happy with his new living situation. Also, he's afraid that maybe he's not supposed to be going over there, that his family wouldn't approve, and the trouble he could get into; neither of them know the full story of why Vilkas lives with Beijeye.

Also, younger Vilkas stealing beer from the fridge, thinks it's gross and doesn't understand how Beijeye can stand to drink it... yeah, that obviously doesn't last. Give it a year or two [and Beijeye's death]