looking askance at
睇 centers on looking sideways or askance, often with a sense of suspicion, disdain, or a sidelong glance.
睇 combines 目 (eye) with 弟, which likely contributes the sound. The character expresses looking in a particular way, specifically a sidelong or askance glance.
The eye 目 on the left and 弟 (younger brother) on the right: imagine an older sibling giving a sideways, suspicious glance at their younger brother, looking askance at what he's up to.
For テイ, picture a teacher (ティーチャー) giving a student a sidelong, disapproving look: teacher -> テイ, and the eye 目 is looking askance.
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squinting; looking closely