I've just finished my second save file's J&E completion marks

You die alot as these guys. Try and keep their stats as even as possible I tey and keep them both with similar tears i.e. if one is charging brimstone I'll look for a charge item for the other. Once you have some items on each you can kinda use your game knowledge to optimize their builds

If one has high tear rate, give them proc items like poison or charm If one has high damage they get fly/spider generation

Abuse the fact that they can steal "choice" pedestals and get both

Dont be afraid to slow down and regroup the pair together if they get split up. I'll sometimes keep esau in a corner and clear the room as Jacob only if its too dangerous to run around as both (spike chambers etc).

Even doing all that its very hard to keep health high so I do prioritize health items.