Author's note: I suppose this should be where I state that I don't own Skyrim, nor any of the mentioned characters/scenarios.
I got my information from a timeline on the Elder Scrolls Wiki page. Thank you so much for viewing and please feel free to review.
Jan-Tu IV was an Argonian who came from a long line of other rather unlucky Argonians. Her misfortunes, it seemed, spawned from a certain series of events that her great-grandmother (the original Jan-Tu) got herself into. That huge mess with Martin Septim all started simply because Jan-Tu had been caught breaking into an Imperial City inn. She was tossed in jail that fateful night and the rest spiraled out of control, thanks to Uriel Septim VII and his grand plan to die. From then on, her Argonian bloodline was doomed. After the battle with Mehrunes Dagon, Jan-Tu was known throughout all of Cyrodiil. However, she remained settled-down in her little cabin found in Leyawiin and married a simple Argonian merchant. Thus, Jan-Tu II was born. Or, preferably, hatched.
Now, the Fourth Era had begun and was well on it's way when the first Jan-Tu decided to have a kid. Divines know why she waited so long. Anyway, time came and went, and Jan-Tu II was only good for one thing: wasting money. She used up all of the riches her dear mother had earned and provided. Eventually, the original Jan-Tu died off, and along with her the wealth of their family. Jan-Tu II was a late child-bearer, as well. Out came Jan-Tu III, born into poverty. It would be safe to say that Jan-Tu III didn't care for her parents. Really and truly, they meant nothing to her. So when the Great War broke out and Leyawiin was the first city in Cyrodiil to go, Jan-Tu III abandoned her ancestor's roots. Leaving Leyawiin behind and heading for Hammerfell, Jan-Tu III accidentally produced a child at quite a young age. Therefore, Jan-Tu IV grew up in the odd tavern and inn.
When the Second Treaty of Stros M'Kai was signed, Aldmeri occupational forces in Hammerfell agreed to leave, which meant the end of Jan-Tu III's life. Jan-Tu IV witnessed her mother's murder at the hand of an Aldmeri soldier caravan. As for her father, well, he fled without a second thought of her. Thus, Jan-Tu IV was on her own.
Nevermind her broken past, because Jan-Tu IV cares about as much as Jan-Tu III did. At any rate, Jan-Tu IV seemed to prefer being alone. Her hatred of the Aldmeri Dominion combined with her lack of anywhere else to go drove her to cross over into Skyrim. Or, at least try to. And that is where our story begins.