Actually, Critical Hits are subject to the RNG, just like To-Hit and Dodge.
Your base chance to land a critical hit is [(Skill / 2) + Class Critical Bonus]. So every 2 points of Skill is worth an extra 1% chance to crit.
This is further modified by:
- Your weapon's critical rate (Weapons with the Killer prefix are especially good for this)
- Your skill in the chosen weapon (0% at anything less than S Rank, 5% for S rank)
- Supports/proximity/Pair Up combinations that directly increase critical chance.
- Skills that increase your critical chance.
- The enemies Luck stat will directly reduce this percentage. (ie. 10 Luck will drop chance to crit by 10%).
The crit rate displayed on the character's info page takes all these bonuses into account, except the opponent's Luck stat. So the simple way for you to figure out your chance to crit is to take that stat, and subtract the target's Luck. You then have a percentage chance to crit.
Most of this info is pulled from http://fireemblem.wikia.com/wiki/Critical_hit#Calculations. It's not specific to Awakening, but from the data I've observed playing, it's spot on.
In order for you to actually GET a critical hit, though, you need the RNG to come through for you twice:
- Once for the actual To-Hit chance (can't get a critical hit if you miss).
- And once for the critical hit itself.
And on the (at the beginning) really low chance you actually score a critical hit, congratulations! Critical Hits do triple damage, which tends to be a one-hit kill.
It doesn't change the story in any way but it does change the amount of enemies and the location of them on missions while making them significantly stronger and with different items + skills. The only way to get different storyline is to change your gender during another playthrough and have the characters marry different people. Please note that I haven't finished my Lunatic playthough but haven't seen any differences so far. Also, this is expected as the script writers had TONS of stuff to write already (most of which you will never be able to read), so this is most likely just a gameplay difficulty.
Spoiler:
Lucina will have different dialogue with you if you are married to her throughout the game. You can also marry Chrom which will produce a slightly different story.
Best Answer
Sadly, those characters only give you one chance to recruit them. If you don't have the correct person talk to them, then you can't recruit them.
Note that this is true even in Casual mode; Casual only flags your characters as unable to die. Until you recruit them, you can definitely kill them, so be careful if you're trying to get everybody.
One thing to do at the beginning of each mission is to run through every enemy; a recruitable characters will have a name and a unique portrait, and not be the boss. Bosses cannot be recruited except through story means, so there's no need to be careful with them.
When you find a character you can recruit, tap their name; it will often give you a hint as to who needs to talk to them to recruit them. Usually it's Chrom, but it might be someone else.
Awakening also has a neat feature where if the person who can talk to them is within movement range, they'll have a "Talk!" icon above their head when you try to move that person. That's new to Fire Emblem; previous versions meant you had to move a person beside the recruitee, and see if a Talk option was available. If not, cancel, and choose the next character. That still works in Awakening, but they make it easy on you with the icon.