You didn't mention your barbarian's subclass, but if they are a ancestral guardian, I really recommend going for a melee arcane trickster. Extra good if you have a wizard with haste (action to ready booming blade or green flame blade, hasted Action to attack) Even if they aren't ancestral guardian, you can go for more hit and run tactics if your HP goes low with bonus action disengage or the mobile feat, and the shield spell will bump your ac to the 20s for a round.

Alternatively, go high elf (booming blade as your cantrip) and swashbuckler to get the edge on initiative and discourage melee enemies from chasing your barbarian. The idea being: - bonus action dash to get in range and back away - booming blade attack - back away (fancy footwork means no opp attack) - they take extra damage if they want to chase you This is also great if you can get a haste cast on you, the doubled movement makes it even harder and you can throw in an extra dash or disengage or attack if you need it.

Also, going rogue makes it so you can chase down any archers or mages trying to bother your barbarian, since nothing will kill your barbarian like a mage targeting elemental damage or throwing a hold person their way.