a snooty list exemplifying the correct use of grammar, to be added upon when i find mistakes in fan fictions.

• i understand that there are many things they forgot to pack, like their clothes and toiletries per say, but they're going to miss their flight if they don't hurry.
• i abhor invitations demanding one to "reply whether or not you are coming." i would much prefer a simple "reply if you are coming," and for you to presume i will not be in attendance if you do not receive my reply. ("whether" expresses condition where there are two or more alternatives, while "if" expresses one where there are no alternatives.)
• this is greater than that. though should you add more to that, then it will be the greater of the two.
• while one cannot truly control their heart, remember who you love is not always to whom you should be giving your affection.
• i shall lay my head on my pillow, ignoring the monsters who lie beneath my bed. then on the morrow, my well-rested head which i laid on that pillow shall give no thought to the monsters who lay in wait beneath my bed.
• rain always affects me badly, causing me to become very, very sad. the effects of the poor weather on my demeanor usually affect the people around me, because i'm too despondent to care about other peoples' feelings. (an affect influences or produces an impression — to cause hence, an effect.)