1.) I feel Lennie is so dependent on George because Lennie tends to take the lead in all of their mishaps. He sort of guides George in a bossy, parental way. From reading the first couple of pages, George has a problem with memory and isn't quite all there in the head. There was a part where George found a dead mouse and wanted to keep it as sort of a companion. Lennie quickly snapped him back into reality and forces him to leave the mouse, until he found a fresh one. I feel like George in some way longs for someone to take the parental role and to give him a plan. something that he has much trouble doing on his own.
2.)I really believe that George would be lost without Lennie. Judging by the first couple of pages in the book, the kind of relationship the have is one that couldn't be possible of on left the other. George needs to be a leader, that's just his personality. He need someone to look after , someone who would follow his exact directions and look up to him as a parental figure. George to me has this loneliness about him , that always needs company. Even if he pushes away with authoritative nature.