Airachnid is from a different timeline called Shattered Glass where the autobots are evil and the Decepticons are good Airachnid lost her sister due to her timelines Arcee infecting her and Black Arachnia  (her sister) where her sister died by giving her the antidote. This made Airachnid very revengeful against the Autobots,  Jack is her human counterpart who accompanies her when she needs it. Her alt mode is a white and pink motorcycle and a spider when she needs to be, she doesn't like to kill