Originally Posted by Coldwater2020:
“Adam and Aaron have never done to each other what Robert and Andy have done to each other. Adam and Aaron have a very loving close relationship. Andy and Robert have a very toxic love/hate relationship that seems to be mostly hate lately and that's ignoring all the stuff that happened before Robert left originally. Just since Robert's return he torched his caravan, killed his wife (albeit accidentally), confessed to killing her and then tried to make everyone think he was crazy and then Andy plotted to murder him. But even with all that I actually think when Robert initially came back Andy seemed far more willing than Robert to let bygones despite the previous bad blood between them precisely because he still saw them as brothers, albeit brothers who didn't always like each other. I think because we're getting a kinder, gentler Robert these days people forget just how awful and antagonistic and really quite petty he was a lot of the time back then. I don't know if Andy would rally to help him these days, I kind of doubt it, maybe if Victoria begged him, but I think he would have done before the Katie reveal.”
I also think the way Robert feels about Andy is a lot to do with how he feels about his dad, and something to do with trying to do what he would have wanted.
Robert refers to him a lot, as do his family when talking to Robert. (Andy says "It's what Dad would have wanted" when asking Robert to come to the wedding; Vic says "Dad would have understood" when trying to get Robert to admit his feelings for Aaron, etc.)
I think Robert does love Andy as a brother, but he also desperately wants his late father's approval, and helping Andy would achieve that.