Possible Clues:

• Stress-free character seemingly calm, having walked away initially
• Upside-down 'e,' in phonetics
• Beginning or end of 'Athena'
• ''Uh'' sound
• The "e" sound in "tandem"
• One's at either end of Alaska
• Inverted "e" phonetic symbol
• What ''agenda'' starts with
• The "a" sound in "about" or "around"
• Sound represented by an upside-down "e"