Lyme was a past victor of an unknown Hunger Games, a Commander of the rebellion in District 2, and a strong independent woman. She was willing to do anything for District 2 to become aligned with the other districts against the Capitol.
Lyme was a past victor of District 2, although it is unknown which Games she won. It was said by Katniss that it was over a generation ago, meaning she most likely won the Hunger Games around the same time Brutus did. She was possibly a mentor for other District 2 tributes, including Cato and Clove, and possibly even Enobaria's or Brutus' mentor in the 75th Hunger Games.
Lyme was one of the first people from District 2 to be a part of the rebellion. She was the Commander of District 2. She cares for the well being of others but can also be cold, as she was willing to do anything to claim District 2 in the rebel army. After they carry out Beetee and Gale's combined plans to make the Nut collapse over itself to block the exits and force the workers out through the train station, while the rebellion retreats back to District 13 after Katniss was shot and the district was in the Alliance, Lyme stayed in District 2, though Coin planned on using her in the raid of the Capitol as she wanted as many past Victors as possible, Lyme was killed either in battle or during the Capitol's Victors' Purge, which in the end left a total of 7 victors alive (Enobaria from 2, Beetee from 3, Annie Cresta from 4, Johanna from 7 and Haymitch, Katniss, and Peeta from 12).
Katniss said that Lyme was middle-aged, over 6 feet tall, and very muscular. She also has a face that was described as unforgettable, as it made Katniss remember her from a past Hunger Games.