Lore:

These are actually clones, now you may be wondering

Why do they look like undyne and alphys

Well in my AU prequel undertale Determined souls

After a few years undyne and alphys got married

But they both been feeling bum...

So alphys wants to have kids, so does undyne

But they don't know how to make some....

So alphys decided to clone them....

But there was one problem...

They have the DNA but....

They didn't know what gender they wanted to be...

But someone offered one...

No one in the underground wanted to give there dna...

Except...

Sans wanted to do it....

And before you ask, yes skeletons have DNA

So he gets a syringe shot to make the DNA work....

But they needed to make sure it works...

And remember when I am doing a shucks version of undertale/deltarune?

Well that sans is a clone...

And the orginal donor is sans....

But that clone had gone wrong, wasn't been cared and became a experiment

Sans wanted to stop the experiment but couldn't...

One day, he escaped....

So many months later...

Alphys have been modifying and alter the DNA to make it work...

And the result....

It worked, it created two clones...

One fish and one half fish-half lizard...

And thus created Mark the scientist and John the Royal Guard trainee

And yeah that is there lore

Know what inspired me to do this?

Well the one thing that inspired me was the clones from star wars the clone wars

As Jango fett was the donor of the clones looking the same

So I decided to do that but make it a little bit different in my AU