The last poem/riddle was about Lord Rassilon!
The people who guessed correctly are TercesTardis and This poet!
The next person I'm doing was chosen by TercesTardis!
I was frustrated by the centuries-long stalemate between the Eleventh Doctor,
and his various enemies during the Siege of Trenzalore.
I and my followers travelled back through time to engineer a psychopath to kill the Doctor,
and prevent the siege from ever occurring.
After Amy Pond's honeymoon,
I arranged her abduction and replacement by a Ganger.
Amy's real pregnant body was taken to Demons Run,
in the 52nd century.
I watched over her through a hatch above the room Amy was held in,
as her linked Ganger lived out her life.
The only problem is this affected the Ganger,
causing her to see me and hear things I said near the real Amy. Everything was going well until Amy's Ganger was destroyed,
waking her up.
I was hoping she'd be asleep for just a bit longer,
but things don't always go as planned.
The People I have done:
The Doctor
Rory
River Song
Cassandra
Rose Tyler
Clara Oswald
Strax
Sarah-Jane Smith
The T.A.R.D.I.S
Missy
Daleks
Donna Noble
Vastra
Weeping Angels
Martha Jones
Slitheen
Tom Milligan
Creature from Midnight
Captain Jack Harkness
Zoe Heriot
The Great Intelligence
Abzorbaloff
Brigadier
Caecilius
Lucy Saxon
Mickey
Van Gogh
Adric
Susan Foreman
Alfie Owens
Ida Scott
Duggan
Romana
Danny Pink
Amy Pond
Lord Rassilon