Frumpkin

Frumpkin is the familiar of Caleb Widogast. Caleb usually summons him in the form of a Bengal cat. As a companion, he is controlled by his summoner, Liam O'Brien, with assistance and communication from the Dungeon Master, Matthew Mercer.

Forms
Although Frumpkin's base form is that of a cat, through the Find Familiar spell Caleb can change his form into various creatures including that of a:
 * Sparrow
 * Octopus
 * Peregrine Falcon
 * Owl
 * Spider
 * Vulture

Background
Caleb Widogast first summoned Frumpkin a few years prior to the beginning of the campaign. Frumpkin was created in the form of Caleb's previous family cat, which he was also named after. He served as Caleb's only friend for a few years before meeting Nott in prison. Caleb considers Frumpkin to be very important to him, and seems to view him as an emotional support at times.

Recalling a previous adventure, Frumpkin had taken the form of an octopus and was used as a cushion to break Nott's fall out of a burning building.

Chapter 9
Frumpkin disappeared in due to a gnoll attack reducing his bird form's hit points to zero. marked Frumpkin's first full episode absence. In the episode following this absence, Caleb resummoned Frumpkin in his cat form.

Frumpkin was kicked by a member of the Crownsguard while trying to get into Zadash's Tri-Spires district, and his hit points were once again reduced to zero.

Chapter 12
As the Mighty Nein sailed from Nicodranas to Urukaxl, Caleb changed Frumpkin's form to a tiny one ounce elf owl and loaned him to Beau. Frumpkin stayed in that form until the Mighty Nein reached Urukaxl. Caleb had him land on Avantika's dagger and attempted to cast Identify through Frumpkin on her weapons while she was sleeping. Avantika was not actually sleeping and immediately killed Frumpkin. Caleb summoned Frumpkin again in the elf owl form.

Caleb Widogast
Caleb loves Frumpkin dearly, and despite his existence as an immortal fey entity, usually treats him like an ordinary pet cat. When not in battle or utilizing Frumpkin's ability to transform into other animals for the purposes of reconnaissance, Caleb will keep Frumpkin draped across his shoulders or loan him to the other members of the Mighty Nein should they require comfort.

Kiri
Whilst Kiri was initially startled by Frumpkin appearing in her arms and somewhat nervous, she very quickly grew enamoured with him and was quite happy to cuddle him, mostly due to his calm and friendly nature.

Nott
Despite the fact that Nott has eaten Frumpkin twice, he does not seem to hold a grudge and is generally friendly towards her, although this might be because of how Caleb holds Nott in high regard.

Yasha
Due to her upbringing in Xhorhas without any pets or many other animals "except the rats, that they ate", Yasha had never met a cat before Frumpkin. However, she shows a fondness for the cat and likes his purring.

Abilities
As a familiar, Frumpkin can appear, disappear, and/or reappear at Caleb's whim (requires one action). Caleb can issue telepathic commands to Frumpkin. Caleb can transfer his senses to Frumpkin, though this renders Caleb's body temporarily blind and deaf. When Frumpkin loses all hit points or when Caleb wants to change Frumpkin's form, Caleb can cast Find Familiar again to bring Frumpkin back or change his form.

Trivia

 * Liam shared his vision of Frumpkin on Instagram (source).
 * Caleb has stated that Frumpkin is never upset over his deaths and has a good sense of humor when it comes to them.
 * The origin of Frumpkin's name comes from a cat of the same name that Liam had when he was a kid.
 * Frumpkin does not require food or drink. However, he will (reluctantly) do so to please his master, such as when he drank from a bowl of milk given to him by Caleb.
 * According to Caleb, Frumpkin prefers his cat form.