Blood Pseudodragon

Keen Senses. The Blood pseudodragon has advantage on Wisdom (Perception) checks that rely on sight, hearing, or smell.

Magic Resistance. The Blood pseudodragon has advantage on saving throws against spells and other magical effects.

Limited Telepathy. The Blood pseudodragon can magically communicate simple ideas, emotions, and images telepathically with any creature within 100 feet of it that can understand a language.

Blood Sense.  The Blood Pseudodragon can Sense blood from more than a mile away and can easily find any being that has blood within a mile.

Blood Mark.   The Blood Pseudodragon can place a blood mark on a singular target to track their movement in a mile radius.

Shadow Dweller.  Blood Pseudodragons can merge with any shadow within 5 ft of itself.

Vampiric Symbiosis.  When someone gains a Blood Pseudodragon as a familiar, they are able to feed blood from themselves to the Blood Pseudodragon to heal it's wounds. 

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage.

Sting. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 4 (1d4 + 2) piercing damage, and the target must succeed on a DC 11 Constitution saving throw or become poisoned for 1 hour. If the saving throw fails by 5 or more, the target falls unconscious for the same duration, or until it takes damage or another creature uses an action to shake it awake.