The captain of a Xyrillian starship that secretly sheltered in the warp wake of Enterprise in 2151 while its engines failed, causing a string of baffling malfunctions aboard the Earth vessel.
Trena'L commands the Xyrillian ship seen in the first-season Enterprise episode Unexpected. With his own engines failing, he hides his cloaked vessel close behind Enterprise and draws on its plasma exhaust, which upsets systems all over the Starfleet ship.
Once discovered, Trena'L is apologetic and gladly accepts Archer's offer of help. Tucker spends three days aboard repairing the Xyrillian engines, and it is during this visit that he unknowingly becomes pregnant after a game with the engineer Ah'len.
Enterprise later tracks Trena'L's ship down again, this time hiding behind a Klingon battle cruiser, so that the Xyrillians can transfer the embryo to another host.