They also took Lot, Abram’s nephew, and his possessions and departed, for he was living in Sodom.
Genesis 14:12 (NASB)
When the kings of Empires captured Lot, the rabbis suggest that they knew exactly who Lot was, and that perhaps they could demand a ransom for him from Abraham.
ויקחו את לוט בן אחי אברם, they made a special effort to capture Lot because he was Avram’s nephew. They were aware of his wealth. They were expecting that Avram would pay a heavy ransom for the release of his nephew.
Sfnorno on Genesis 14:12:1