Countess Marika Neagle was a Warlord with the flying special in service to Faq, who worked with Jillian.IPTSF Text 29 She was killed in action during the Battle for Blitzkrieg Bop over a hundred turns before the events described in 'Inner Peace'. Jillian regretted losing Marika as they made an excellent fighting team.
Jillian and Marika were lovers.
Marika was an early, if not the first, lover that Jillian had. Their relationship was intense but started to spill over into their work in the field, which lead to problems. Lover's spats became insubordination, and in the end Marika ignored Jillian's orders and was croaked at the Battle of Blitzkreig Bop.
This was Jillian's first lesson in the importance of keeping her work and personal lives separate, though not her last.
Real World References
Her name is probably a pun on 'American Eagle'. Whether this is a reference to the American Airlines' American Eagle brand or to the American Eagle Outfitters is unknown. Given her temperament it may be an oblique reference to the tendency towards belligerent foreign actions by the United States of America, which uses the Bald Eagle as its national emblem.
This may just be a simple reference as Marika Neagle is known to be a flying unit.