at sb's

At sb. 's service -- willing to help sb.

We may drink wine at sb's wedding.

Be trouble at sb's presence.

stay the night with sb, ie sleep at sb's house for the night

at the request of sb = at sb's request:

Pay homage at sb's mausoleum

blink at sb. 's sudden fury

Throw oneself at sb's mercy

Be amazed at sb's assurance

Be offended at sb's remarks

Be shocked at sb's conduct

strike at sb. 's vitals

direct a blow at sb's head