<p>This contains major unmarked spoilers if you've only watched the anime, as will the linked questions.</p>
<hr />
<p>In Eren's case, it's through a particular serum that his father injected into him just after the fall of Shiganshina, shown in chapter 71 of the manga. This serum was stolen from the <a href="http://shingekinokyojin.wikia.com/wiki/Category:Reiss_family" rel="nofollow noreferrer">true royal family</a> by Eren's father, and is used to allow the subject to turn into a titan. As well as Eren, Rod Reiss is also shown as being able to transform after he has some of the serum:</p>
<blockquote>
<p>&quot;...he himself scrounges the fluid off the floor[...]. After ingesting it, he turns into a gigantic Titan considered by Levi and Armin to be bigger than the Colossal Titan.&quot;</p>
<p><sub> <a href="http://shingekinokyojin.wikia.com/wiki/Rod_Reiss#Story" rel="nofollow noreferrer">Rod Reiss</a> on the SnK Wiki</sub></p>
</blockquote>
<p>Certain humans that are also 'titan shifters' seem to have this ability inherently, or at the very least, it hasn't been covered as to where they gained it - this includes the likes of Annie, Reiner and Bertholt.</p>
<p>Additionally, if a titan shifter is eaten, a titan with a human inside will gain the ability to shift between two forms. This is evident in the case of Ymir, discussed in <a href="https://anime.stackexchange.com/questions/17210/how-does-ymir-turn-back-into-her-human-form"><strong>this question.</strong></a></p>

CC BY-SA 3.0
2015-08-04T12:15:43.087Z
I think you might want to cut off the second part of your answer.
nhahtdh
CC BY-SA 3.0
2015-08-04T12:23:06.967Z
@nhahtdh Thanks for the notice, I wouldn't have seen the edit for a while if not
Matt
CC BY-SA 3.0
2015-08-04T18:00:24.470Z
Titan shifters are still titans, just in their human form, so they don't really *turn* into titans anymore, they just *morph*. As far as I remember, the serum is the only way to turn humans into titans.
Peter Raeves
CC BY-SA 3.0
2015-08-04T18:02:08.363Z
Ow and when you (or Rod Reiss) say *eat*, you mean more accurately "Bite through his spine. It's enough just to ingest his spinal fluid". I love that quote and you also read more about this [here](http://teetanjaeger.tumblr.com/post/122949092597/on-cerebrospinal-fluid-spinal-cords-and-titan). Not that I actually read the blog post, but it seemed interesting and relevant.
Peter Raeves
CC BY-SA 3.0
2015-08-04T11:47:43.157Z
2015-08-04T12:24:08.890Z
2020-06-17T09:17:53.303Z
Matt
<p>I'm currently only watching the anime. I hardly read the manga but I'm very curious as to how humans become titans. Is it by some kind of drug similar to the one Eren was injected with by his father?</p>

CC BY-SA 3.0
2015-08-04T11:03:48.690Z
Try to ask single question at time and for how humans became titan ,there are some question related to it , you might get answer but with spoiler and about Anne's try to ask those question separately
mirroroftruth
CC BY-SA 3.0
2015-08-04T11:13:54.733Z
Also you could try to change a little bit the question in general, because you are saying "Attack On Titan - Female Titan" but you are interested about how any human became a titan. Maybe it could be like "How humans became titans?"
pap
CC BY-SA 3.0
2015-08-04T11:32:12.063Z
I edited your question so that it only asks the first real question you asked.
SWard
<attack-on-titan>
How humans became titans?
# How humans became titans?
Posted by: username_0 on 2015-08-04
I'm currently only watching the anime. I hardly read the manga but I'm very curious as to how humans become titans. Is it by some kind of drug similar to the one Eren was injected with by his father?
**Tags:** attack-on-titan
> **Comments:**
> **username_1**: Try to ask single question at time and for how humans became titan ,there are some question related to it , you might get answer but with spoiler and about Anne's try to ask those question separately  
> **username_2**: Also you could try to change a little bit the question in general, because you are saying "Attack On Titan - Female Titan" but you are interested about how any human became a titan. Maybe it could be like "How humans became titans?"  
> **username_3**: I edited your question so that it only asks the first real question you asked.  
---
## 1 answers
### Answer by username_4 on 2015-08-04. Score: 3 | Accepted answer
This contains major unmarked spoilers if you've only watched the anime, as will the linked questions.

---

In Eren's case, it's through a particular serum that his father injected into him just after the fall of Shiganshina, shown in chapter 71 of the manga. This serum was stolen from the [true royal family](http://shingekinokyojin.wikia.com/wiki/Category:Reiss_family) by Eren's father, and is used to allow the subject to turn into a titan. As well as Eren, Rod Reiss is also shown as being able to transform after he has some of the serum:

> "...he himself scrounges the fluid off the floor[...]. After ingesting it, he turns into a gigantic Titan considered by Levi and Armin to be bigger than the Colossal Titan."
>
> [Rod Reiss](http://shingekinokyojin.wikia.com/wiki/Rod_Reiss#Story) on the SnK Wiki

Certain humans that are also 'titan shifters' seem to have this ability inherently, or at the very least, it hasn't been covered as to where they gained it - this includes the likes of Annie, Reiner and Bertholt.

Additionally, if a titan shifter is eaten, a titan with a human inside will gain the ability to shift between two forms. This is evident in the case of Ymir, discussed in [**this question.**](https://anime.stackexchange.com/questions/17210/how-does-ymir-turn-back-into-her-human-form)
> **Comments:**
> **username_5** (2015-08-04): I think you might want to cut off the second part of your answer.  
> **username_4** (2015-08-04): @nhahtdh Thanks for the notice, I wouldn't have seen the edit for a while if not  
> **username_6** (2015-08-04): Titan shifters are still titans, just in their human form, so they don't really *turn* into titans anymore, they just *morph*. As far as I remember, the serum is the only way to turn humans into titans.  
> **username_6** (2015-08-04): Ow and when you (or Rod Reiss) say *eat*, you mean more accurately "Bite through his spine. It's enough just to ingest his spinal fluid". I love that quote and you also read more about this [here](http://teetanjaeger.tumblr.com/post/122949092597/on-cerebrospinal-fluid-spinal-cords-and-titan). Not that I actually read the blog post, but it seemed interesting and relevant.  
---
