I just have two questions

1) why do people make sentry a separate person from Bob? I think that it's just bob with his ego a little stroked, but it looked like bob in general (in canon) (of course I love reading everything about sentry as a different personality, it's just that I wonder that sometimes)

2) why do people tend to change his hair colour to blond when sentry appears? In theory it was just dyed, nothing magical, well the magical thing was that the dyed hair couldn't survive the void

Sentry is the pinnacle of manic episodes, Bob's happiness and confidence taken to excess.

Void is depression.

And these two states alternate, sometimes for months.

Fun fact: I have a friend with bipolar disorder and I see it working.

We've explained how it works in reality.

But ehi, Bobby DOESN'T EXIST.

If someone in a fanfic wants to give him gender identity disorder instead of bipolar disorder, they can do so, because it's fiction.

In Italy, it's called creative license; it's literally playing with dolls.

As for the blonde hair, as mentioned before, creative license.

But if he wanted to—and that's the cool thing—the Sentry could actually change his hair color, as a deity capable of controlling matter in its atomic state.

This hasn't come up much in the discussions, but did you notice that when Bobby died, he was wearing different clothes, and then when they emerged from the Void, the clothes he was wearing in the Void arrived in reality?

He is a fucking God. He could change his appearance into a frog and it would still make sense.

That said, I also like to remember Loki's sacred words: I do what I want.