Due to a Situation, Odette was forced to leave her brother behind in the messed up future, and travel to the past without him

Odette Speex: Time Traitors Book 1 - Padgett Lively

She's in 1750s London to make sure the murder of Benjamin Franklin is averted.  His murder was the first in the string of events orchestrated by Westchester to convolute the timeline.

 

"She had lain awake for hours rehearsing her method of interrogation. She wasn't quite sure what approach to take. Maybe the 'indignant about the intrusion' approach or 'scared about the intruder' approach or the 'wasn't it so exciting' approach but none of them seemed right. She wanted to use the 'I was dressed up as a boy last night because I'm a time traveler from an alternate history and I'm trying to make everything right again' approach, but knew that was a nonstarter."