Pillow

Pillow can be impulsive and care little for others, such as licking Lollipop out of hunger and randomly picking up Book to look at the pictures. She is shown to be apathetic as she was very casual about dipping Price Tag into acid in "The Worst Day of Black Hole's Life". She didn't seem to be capable of knowing why Price Tag would have a problem with this and nonchalantly says "That's fine" when Price Tag says they'll die.

BFB

Pillow is apathetic, carefree, and eccentric. Similar to Golf Ball, Pillow is interested in research. Her research is seemingly random and made up, such as when she misinterprets Teardrop's arm fluttering as "not caring", suggesting that it's due to "care spirits" leaving her body. She seems to enjoy taking notes, as she can be seen writing in a sketchbook when Donut infected himself with the Twinkle of Contagion, although Pillow's Official Character Guide biography mentions that she doesn't know how to write, hinting that she might draw pictures instead.[note 1] It's also hinted that Pillow is illiterate, as she picks up Book to look at the pictures instead of reading her.

Pillow also seems to have a morbid interest in death and destruction. In BFB 1, she only joined Death P.A.C.T. because she heard the word "killing".

TPOT

Pillow’s fascination with death remains central to her character in this season. In "The Seven Wonders of Goiky," she reveals that if she won the limitless power, she would use it to "study how many people would be blown up with just one zap," implying a morbid desire to harm others for amusement. She believes she is more likely to succeed by killing rather than helping, as seen when she expresses a preference for damaging her team's rollercoaster instead of repairing it.

Her addiction to violence seems to stem from an unknown event between BFDIA and BFB, as she claims in "PointyPointyPointy ♫" that she would never willingly advocate for such actions. Pillow sees killing as a form of good luck, which drives her to try it repeatedly. However, after causing her team to lose in "Outbreak At Stake" and hearing that Teardrop was eliminated due to her death, Pillow begins to regret her actions, realizing her belief in killing as good luck was misguided.

Despite this, Pillow remains disgusted by the idea of doing good deeds and refuses help, even puking fluff at Book in "Oneirophobe's Nightmare." She tries other methods of good luck, like showing kindness, but continues to display her violent tendencies in smaller doses. She torments Bomby with a blender and kills Donut in "Category One." However, her violence is occasionally used to her team's advantage, such as when Winner gives her a flamethrower to kill the Dragons on the Hotel's roof.

Her killing is nothing personal to the victim, as shown as how she is friends with people she's killed like Book, Bomby, and Price Tag, but she still keeps killing them. It is also shown by the fact that she didn't see the problem with putting Price Tag down in acid. The fact that killing isn't personal implies that she would be perfectly fine with it if someone wanted to kill her for fun.