I've seen a lot of comments about how he should be a character in your orbiter. The thing is, he is not actually sentient, in any meaningful way. DE likes to keep things vague and doesn't really do "consistency" but as things currently stand:
Every Warframe has some degree of sentience. The Tenno pretty much stamp that out, when they "bond" with a warframe. Warframes are all broken monstrosities, since they're made by infecting people with an alien super-virus, and then they were all subjected to various forms of torture and experimentation to try to control them. Their default state of being is suffering, and Tenno–through their void magic and also the power of friendship–suppress that. Ballas states this explicitly in The Sacrifice. Additionally, it lines up exactly with what we've seen. Proto-Rhino went on a murderous revenge-rampage till the Tenno's presence calmed him down. And Umbra did the exact same thing, except it took more work to calm him.
Umbra's shown the most independence of any frame so far, and the reason for that is that warframes only have consciousness in the form of basic instincts, and thus their consciousnesses emerge most fully when those instincts are triggered by extreme circumstances. Ballas, being the dick that he is, engineered Umbra's creation to center around the super traumatic experience of killing his son. His consciousness was pretty much reduced to that memory, and thus he had a kind of self-sustaining rage-loop that kept him more active than most frames. Where else do we see a frame demonstrate some sentience? In TSD, under the pretty extreme circumstances of being murdered by senpai stalker. Whatever frame you used there is canonically one that you've presumably used a lot, so its instincts have mostly shifted to "protect the operator", which makes sense since you are the reason it isn't just a ball of rage and suffering.
Umbra obviously goes through that same transition, and in fact ends up with a much stronger protection instinct as can be seen when he guards you from the Lotus in that last cutscene, and of course how he follows you around. This is because A. as stated earlier, Ballas purposefully instilled him with more emotions/consciousness than most frames, making him harder to subdue, and B. you are a child and Umbra's memories/remaining sentience are focused around his son–and thus purely by coincidence your presence kind of acts like a trigger for him, except in a positive way since he can protect you where he could not protect his son.
So in summary, Umbra retains a bit more sentience than most frames, but he is not a person. He's more like a dog that sleeps a lot and also vaguely believes it's your father.
Feel free to point out issues with this, but keep in mind that DE has already contradicted themselves multiples times in the lore. There is not going to be any sort of perfectly consistent "unifying theory of Warframe" and I'd say this is the best explanation based on what we know.
Edit: btw this isn't actually an argument as to why Umbra shouldn't be able to walk around the Orbiter, just a discussion of why it makes sense that he got put in storage at the end of the quest. I want more orbiter friends, even if they're just technocyte zombies.
Source: Original link
© Post "Regarding Umbra walking around the orbiter" for game Warframe.
Top 10 Most Anticipated Video Games of 2020
2020 will have something to satisfy classic and modern gamers alike. To be eligible for the list, the game must be confirmed for 2020, or there should be good reason to expect its release in that year. Therefore, upcoming games with a mere announcement and no discernible release date will not be included.
Top 15 NEW Games of 2020 [FIRST HALF]
2020 has a ton to look forward to...in the video gaming world. Here are fifteen games we're looking forward to in the first half of 2020.