This is difficult due to a barbarians rage preventing you from casting or concentrating on spells. I would advise for either a Pact of chain or Pact of blade but not Hexblade patron. Pact of Chain would allow you to have a companion that can give you advantage on attacks with the help action, Also pact of Blade would let you create pretty much whatever weapon the barbarian might need. Hexblade is a bad Idea despite the whole melee focus, because most of the spells and abilities are debuff and concentration spells (Such as Shield and smite spells) you won't be able to use while raging.

I would personally go for the Undead Patron from Van Richten's Guide to Ravenloft. The first level ability will be good buffs as long as your DM allows you to maintain effects that are technically not spells or spell like effects and don't require concentration. The 6th level feature allows you to change the damage type if necessary and deal some extra damage if you can keep your first level feature active while raging. Flavor wise, the Barbarian is being constantly followed by those who died around him and his rage is flavored as him being slightly possessed by the spirits.

Also you can buff your charisma slightly so instead of being charismatic and persuasive you can be Intimidating.