This might not be what you're looking for, but it can be quite handy anyway: you can put a video clip in the trimmer and then add markers there, and they will appear inside your video clip wherever you put it.
These markers don't have the same capability as regular timeline markers, but I think can be "promoted" to timeline markers by a script.
But anyway, they are very useful for marking beats in music, or events in a video clip, such that no matter where you move the audio or video event on the timeline, the mini-markers are embedded in it and move with it.
(The Ripple Edit suggestion - had to edit it having just seen/read TimL) But it will also move any media further down the track too. Ripple Edit is a track tool, not solely an Event Tool. Added to which, if you move an on another Event, that option to MOVE Markers will also move the marker away from the Event too. That would be useless for your requirements.
Lock a Marker to an Event? I can only think of rendering the Event and save the marker so that it is embedded with THAT Event and in which case the marker becomes ineffective as it is "encased" within the Event and looses its ability to perform as a marker - until you use the script to promote it back again. So, IMO, this makes the Ripple unsatisfactory for solo Event-centric work.