返

Walking radical wrapping the bottom-left, the simplified three-stroke form of 辵 (a foot stepping along a path). The indexing radical, planting 返 firmly in the motion family alongside 进 to advance, 退 to retreat, 还 to return, 追 to chase, 逃 to flee. Any character with 辶 is some kind of going-and-coming.

Inside 反 supplies the sound exactly: fǎn → fǎn, identical pinyin and tone. 反 also pulls strong semantic weight, it depicts a hand turning something over (厂 cliff + 又 hand), giving the meaning 'reverse, flip back.' 返 is the motion-version of that flip: to turn back, return on one's path. Pure phonetic-plus-meaning overlap, an unusually transparent pairing.