No exceptions really is the fairest rule.
Once you cave and let someone pass you do a disservice to all those you denied previously.
Exceptions require secrecy and also set you up for future arguments.
‘Well you did it for them, why can’t you do it for me?’
In that case replies like ‘well they had a really sad sob story and yours is only kinda sad’ or ‘I was feeling particularly sentimental at the time’ or ‘see they kicked up a fuss’ won’t end well for you.
Thomas Duggan 