Under-facts: Undyne and the Amalgamates similarity

bath
Undyne is a fish
COINCIDENCE
I THINK NOT!

no one actually knows why undyne has dt. it actually never says who did it, or rather, what happened. perhaps undyne is so determined to stop you, she gets dt. or maybe alphys really did inject her with it. sooo... we will never know canonically why undyne the undying has dt.

Remember what the purpose of Alphys injecting determination to the monsters, to make it more stronger and can be break the barrier. But unfortunately, monsters are different than humans... and than it makes the monsters are melting. Undyne probably didn’t determined a lot because if Undyne has been very determined, she must be already be a amalgamate. And thats why the amalgamate are more undying than Undyne because the amalgamates are fully or mostly injected with determination by Alphys.

yea that too. but we dont know the source of undyne's slight determination.

We actually see her producing dt when she is transforming she goes from holding on by a thread being basically dust to soowly reforming representing her dt rising meaning she does produce it on her own otherwise if it was injected she would reform instantly she isnt an amalgamate bec you cant kill those gut you can kill undyne