<human>: Can you give me the gist of the text in a nutshell?

I recently got back together with an ex of mine after 4 years, and long story short; It's more than likely not going to end.

In this process, I will be taking on a stepdaughter who is 1 year old. The father wants nothing to do with my gf or his daughter, so for all intents and purposes I will be her sole father figure. Is there anything I should know in advance? I'm absolutely excited that this is happening as well as my gf who until now had consigned themselves to a life of just the two of them. She told me she doesn't want to put ANY responsibility on me aside from just being there and showing her what a good person should be like. Obviously I plan on being way more involved then that, but is there anything I should know? prepare for?
<bot>: GF's 1 year old daughter has a deadbeat dad and I will be accepting the father role in her life? What do I need to know?