WE don't talk about E-999-A-yay-yay. We don't talk about E-999-AAAA. BUT-

It was a normal day
And we were getting ready for testing and there wasn't a cloud in the sky

But then the doctor walks in with a sinister grin...

OH NO!

He says it's time to test
He needs another sample
They put it in the machine and then
A new SCP exits with hostility...
(Not sure if I did this part very good)

uh oh time to contain this thing

999's pissed off!

What is scp 999-A?

It's E-999-A, a creature made from samples collected from SCP-999 and then passed through I think it's SCP-914 (The Clockwork machine or something, haven't done this in a while), and so it came out, it doesn't like people, and SCP-999 doesn't like it.
So it ate it.
And if any researcher even mentions E-999-A, SCP-999 starts ignoring that person, like it's grumpy or sulking