writhe, struggle, be impatient
踠 centers on physical twisting and struggling, especially with the body or limbs, often from pain or impatience. The idea of writhing extends naturally to mental agitation and being unable to stay still.
踠 combines 足 (foot) with 宛, which likely contributes the sound and may relate to bending or curling. The exact historical development is uncertain, but the character is associated with writhing or struggling movements of the feet or body.
The left side is 足 (foot), and the right side 宛 looks like a person curled up under a roof. Imagine someone writhing on the ground, feet kicking and body twisting impatiently.
For エン, picture a person writhing in pain and saying 'ennn' (like a groan). The sound 'ennn' cues エン while the body struggles.