You have picked up a weird little guy as a pet in your strange planar travels. He hangs out on your back. He holds your stuff like a backpack and he also has a real big eye. Where'd this weird little guy come from? Is he a Beholder? Is he a little demon of some kind? Where did he come from? You don't remember, but you and this weird little guy have formed a symbiotic bond.

Symbiotic Hitchhiker. Once per Long Rest, you can roll a Perception check with Advantage.

Weird Little Mind. You can understand the languages that this weird little guy can understand, but his mouth is not physically articulated in such a way as to allow speech.

Weird Little Attack. Once per Short Rest, this weird little guy can use one of your Bonus Actions to unleash a tiny Enervation Ray against an enemy directly behind you. The spell has a range of 10 feet which cannot be increased by any means. Target takes 1d4 Necrotic damage. Target makes a DC12 CON save. On a successful save, damage is halved.

Weird Little Bite. If anyone is stupid enough to get close to your weird little guy, they're gonna get a weird little bite. If a creature is within 5 feet of you and is wholly behind you, this weird little guy can use one of your Bonus Actions to make a Bite Attack. This attack is made with disadvantage and the target gets a +3 bonus to Armor Class. The attack cannot critically hit. On a hit, the target takes 1d6 Piercing damage.

Watch Your Back!  Once per Long Rest, if this weird little guy is your pet and a creature is about to make an Attack Roll with Advantage against you, you can use your Reaction to cancel that Advantage.