My son started a leveling a tank a dwarf warrior, and I started a gnome mage to level with him , but by 20 I hated being a mage ( I find it fun to solo as frost but not fun in groups) and switched to a pally healer so I'm his pocket healer. He's surprisingly good, rarely loses aggro makes good pulls and never lets me get my face smashed up by a lot of mobs. We've pugged to about 50 now ... the only issue he had was forgetting my mana ( no, I won't really ground him) and when there was some confusion about real life water and in game water ( it's hot and well I was thirsty, but I meant I needed to drink in game). we've survived a couple of crazy pulls like when that rogue dug up seven graves in ZF while I was drinking ( I let the rogue die) the rest of us all lived and it was fun.
One particular benefit is we are in the same room, so we have fairy clear voice communication, the tank healer trust level is pretty high so at points where I've seen other tanks freeze up we just keep going and pull through ( see this on my main healer a pull goes bad, and the tank just says we're all gonna die, and just stands there. I never understood this , why stop trying how else will you have those great tales to tell if you don't try<3 Lorsty for all the crazy amazing storys we have).
The groups were all surprisingly civil, I remember discussing with him at level 15 how people are mean to tanks and try not to be too distressed if they act like asses, then we hit the random LFG and were off only one super obnoxious hunter who someone else started the vote kick on before I could. It's been a lot of fun and when his papa (80 warlock) and sister (62 boomkin/kitty) join us someday as DPS, or rather we join them as we catch up we will have family fun.
He's planning a healer next and I'll give tanking a go, it should be interesting.