Well to put things simple I am going swordsman with a shield not sure if I should stick with spear or sword but anyway what class is a great synergy other then the hole “tank being supported by a healer”.
At the moment from the class description I will go Peltasta and direct my brother to go with Creomancer or Elementalist Is this a good idea?
tank and an archer is pretty good too.
I’m in a similar situation, I’m going into swordie - peltast - hoplite 3 - doppler 2 and my lady will be playing with me but I did not like the idea of her just healing me and being full support as thats ultra boring. So I found the best of both worlds for her, she can heal me and also kill stuff solo or with me ( even better with me cause of taunt keeping mobs close ). So if you want to have synergy between a tank swordie and a possible other person, this is my proposition.
woot woot zombie master with a healing twist 
Yeah but no zombies, just hex and effigy spam.
Also, plague doctor’s healing factor is a Really good heal, like really good. So until rank 6 its 2 ranks of cleric for the heals, which honestly should be enough even more since its an int build and later on healing factor kicks in and you two should be golden.
Hope it helped, though I’m not saying it’s the best thing out there I’m just saying that’s the conclusion I came to when faced with the problem just to keep both people interested in the game 
wha no zombies 
also I noticed two things you can have 18 zombies and wheelchair zombies/big zombies now I’m interested in making a bokor…