Follow Your Passion: A Seamless Tumblr Journey
Young Hugo with a group of other orphans on their way to steal from Donella. They succeed, somehow, and Hugo has the treasure/whatever thing they stole. But Donella's soldiers are chasing them. Not everyone is gonna make it out. One of the kids asks Hugo for the treasure thing, and Hugo throws it. The kids are now within reach of the soldiers. Hugo is about to catch up to the other orphans when one of the kids kicks the wall hard and a ton of heavy supplies and machinery fall on Hugo. That, is how Hugo lost his leg (in my fic anyways)
Also Olivia gets a little dented here but she gets saved by one of the soldiers or Donella herself, and then Hugo reunites with her after he wakes up
Donella also makes Hugo's mechanical leg and teaches him how to make it stronger (though he really uses this knowledge on Liv, despite how much Donella makes it clear she thinks the mouse is useless)