sad news...

Not too long ago,  I was made Thane to the Hold of Whiterun.  This honor was bestowed upon me because I eliminated a dragon that was harassing the city of Whiterun.  One of the perks for such a position was my own bodyguard (Housecarl)... Lydia. 

Lydia was very aggressive, immediately attacking anything that was a threat to me and only remaining by my side (or behind me) when I specifically told her to "wait here".   I really should have been more careful, but on an adventure into an abandoned mine, she pushed her way ahead of me to fight someone I had already engaged in combat.  One massive power attack (from me) to her back ended her life.  Filled with shame and guilt, I very slowly made my way back to Whiterun (some of the slow moving could have been partially due to lugging all that extra gear and booty Lydia had been carrying).

I believe it may be best never to have another follower.. putting only myself at risk.  At the very least I will re-think what follower to have along with me... perhaps one who excels with ranged weapons may be a better alternative... while I handle any melee.  Or simply, when necessary, rely on conjured creatures/weapons and/or other spells.  Perhaps a pack-mule, to help carry everything, would be a better choice... leaving them outside (tight fitting places) and exploring on my own.

Lydia following me through some very cold water.
(She never complained... she needed a bath anyway.)