Cunning, resourceful, aggressive in combat, diplomatic when necessary, dogged in pursuit of duty and fantaically loyal to the cause -- all qualities greatly to be desired in a Starfleet officer, but quite a nuesance when found in an opponent.  Especially when that opponenet is a Romulan, a race which prizes craftiness and strategic deviousness above all else.  Officers with these talents tend to face off with their opposite numbers across hotly-contested borders, which is why Captain Jean-Luc Picard and William Riker of the U.S.S. Enterprise keep running into Romulan Commander Tomalak.

In 2366, when the Romulan two-man scoutship Pi crashed on Galorndon Core, on the Federation sid of the Neutral Zone, it was Tomalak's warbird that answered its destress call.  Undaunted by the Enterprise's response to that same call, Tomalak took it as an opportunity to pressure Captain Picard.  Tomalak simultaneourly tried to protect the spy mission by denying all knowledge of it while claiming that Picard's presence was a violation of the Neutral Zone treaty.  If Picard had mishndled the situation, Tomalak could have parlayed it into justification for an all-out Romulan incursion.  Forunately for the Federation, Picard didn't rise to the bait.

Later that same year, Tomalak's scheming was behind the defection of a Romulan Admiral.  Already disgraced and isolated for his opposition to certain policies of the High Command, Admiral Jarok fled across the Neutral Zone to prevent what he believed was to be a full-scale invasion into Federation space.  But all his information was false -- plans, manifests and communiques faked by Tomalak to test Jarok's loyalty and create a trap for the Enterprise.  When Picard arrived at Nelvana III to look for the suspected Romulan base, he found himself trapped by two Type-B warbirds under Tomalak's command.  Tomalak insisted on Picard's surrender and boasted that the stripped hull of the Enterprise would become a Romulan trophy.  If not for Picard's foresight in enlisting the aid of cloaked Klingon ships as backup, Tomalak's boast would have become a reality.

In 2370, Tomalak commanded the Terix, one of 30 Romulan warbirds that hastened to the Neutral Zone in response to the appearance of a dangerous temporal anomaly caused by Jean-Luc Picard in the Devron system.  In the face of possible crisis, Tomalak cooperated with the Federation in order to investigate the anomaly.