וַיּ֥וֹאֶל הַלֵּוִ֖י לָשֶׁ֣בֶת אֶת־הָאִ֑ישׁ וַיְהִ֤י הַנַּ֙עַר֙ ל֔וֹ כְּאַחַ֖ד מִבָּנָֽיו׃
And the Levite was content to dwell with the man; and the young man was unto him as one of his sons.
Read midrashic interpretation of Judges 17:11: and classical rabbinic exegesis.