If you clicked on this thread expecting to find raucous smut, let me stop you right here. By "mature" I mean "won't lose your head when approaching themes you disagree with." I like my plots to be twisted and meaningful, and I need someone with the mental and emotional maturity to write them. Now onto pairings and plots!
Soldiers A and B are young new recruits in the King's army. A is a serious guy, B is something of a joker. The two hit it off and become close friends. Once they get out of basic training and hit the battlefield, they find that the Kingdom is in a very desperate situation. The enemy army has a magical Chosen Hero to fight with them, and he has been crushing the opposition. It's up to you and your comrades to save your kingdom - and each other. Note that there is to be NO MxM romance here.
The Kingdom of Dragan is unstable. The man who conquered it, Lord Dragan himself, is getting on in years and wants to leave it to someone capable. Princess F is his daughter and only child, so he decided that he would betroth to her and nominate as crown prince whoever was able to defeat all the other suitors in a contest of arms. Prince M is from one of the tribute states in the kingdom and is victorious. Unfortunately for the young couple, not everyone is satisfied with the outcome, and escaping the palace is not an option if one desires a strong and happy kingdom, locking the palace in a political deathmatch where only the smartest survive. Both M and F's lives are at risk, forcing them to defend one another in any way they know how.
The whole world is ruled by an oligarchy of four elves, who often travel abroad to stop the uprising of evil. You, male elf M are one of the four. Long ago, you became betrothed to one of your fellow ruling elves, female elf F. Some time after, a crisis arose in two places and, being the only two elves left to handle them, parted ways, never having consummated their marriage. Now, after many years apart, F has returned, having received word that M will soon be facing a mighty sorceror alone. Old alliances will be shattered, and old friends will become enemies. The fate of the world hangs in the balance.