The sheikh is ready to flee if the Lebanese security forces, considered to be in thrall to Hezbollah, make a move to arrest him.
If you want to live in the United States, somewhere along the line you will fall under the thrall of the federal government.
Each party is in thrall to certain of these interest groups.
Old English þræl "bondman, serf, slave," from Old Norse þræll "slave, servant," probably from Proto-Germanic *thrakhilaz, literally "runner," from root *threh- "to run" (cf. Old High German dregil "servant," properly "runner;" Old English þrægan, Gothic þragjan "to run").