As we see from the Manga

when Eren ate his dad and when Armin ate Bertolt, they immediately transformed into a shifter-titan.

But when Eren gets eaten in Season 1, how is it that the titan who ate him never transformed. Plus Eren was inside his stomach for a while before he transformed and killed him.

  • I just hope I didn't read some spoilers to S3 in the title.
    – Zereges
    Commented Apr 17, 2018 at 22:03
  • @Zereges Be thankful then I added the spoiler tag to the question. But the Santa Titan is commonly referred to the titan that ate Eren in S1 Commented Apr 17, 2018 at 23:45

2 Answers 2


The proper requirement to gain the powers of a shifting Titan is to drink the spinal fluid of the Shifter. This is revealed on chapter 65. The "Santa" Titan didn't gain any powers because he ate Eren whole.

When Eren ate his father, he bit him on the waist, severing the spine and getting access to the fluid. Armin bit Bertholdt on the head.

  • 1
    I added spoiler tag because, being the same spoiler in the question, it contains heavy spoilers not shown in the anime yet Commented Apr 18, 2018 at 3:27
  • Well whole-ish.
    – IG_42
    Commented Apr 25, 2020 at 9:32

On top of drinking the spinal fluid, the shifter also needs to die at roughly the same time. Otherwise the power would just shift into a random eldian baby. This is why, when the beast titan gives his spinal fluid to a bunch of different towns people and government officials in the walls, they don’t turn into the beast titan when he activates them, they turn into regular titans, so it’s a bit of a process, but that’s ultimately why the titans eat people. It’s in their nature to eat and kill humans until they eventually eat a shifter. It’s not a conscious decision, but more of an instinct because they all ultimately come from the same being, and so they all have a shared knowledge that they act on without any will to control this. We see only two pure titans who fight this instinct off but neither of them are able to for long.

  • 1
    Please include relevant sources/references support your answer.
    – W. Are
    Commented Apr 30, 2020 at 11:28

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