Becoming the Mask: L really does become friendly with Kira and Light spends so much time playing nice around L and the orphans he becomes a Papa Wolf for them.
Did Mom Just Have Tea with Cthulhu?: When Misa arrives at Wammy's House L panics because before when it was just Light they were reasonably safe since they were all using aliases. But now that the Second Kira is here Light can find out the true names of the children and kill them all if he wanted to.
Did We Just Have Tea with Cthulhu?: The entire time. Near is mystified when pondering the fact that KIRA just ruffled his hair, as is Mello when he made them cocoa, etc.
Later L invites Beyond Birthday to come join them for Christmas.
Double Date: Light and L with Misa and Hideki Ryuuga.
Easily Forgiven: L invites Beyond Birthday to join them for Christmas dinner and eventually he comes to forgive Light for being Kira and reciprocates his feelings.
Lima Syndrome: Light comes to like and become very protective of the Wammy Orphans and becomes really insulted when L suggests that he would ever try to kill them.
Papa Wolf: Light becomes this for L and the Wammy's kids.
Light: I will also keep the Death Note where I can reach it whenever I need to, because I will need that power to protect you and our orphans. But... would you, and could you, perhaps, consider... combining Kira and L's powers?
L: What, as in, 'Quit killing, or I'll set Kira on you'?
Scarpia Ultimatum: Subverted but brought up. When Misa comes to the Wammy House and L realizes that now Light has all the names of the kids, he offers his complete obedience to Light and when Light asks if that also means sex, L agrees. Light however, upset that L thought he was going to force him into sex for the orphans safety, pushed him away.
Secret Identity Identity: both Light and L have this little crisis- Light wants L as his boyfriend but also wants to be God of the New World and L is his main obstacle. Meanwhile L the Detective wants to arrest Kira but L the person has also developed feelings for Light...
Seen It All: Light is completely unfazed upon meeting a ghost.
Subverted Kids Show: Near was making some finger puppets of those he considers family. Light is surprised that that includes him, but then notes that it's sitting not so innocently on his middle finger.
Talking to the Dead: L expresses his concerns about entering a relationship with Kira to A and B's graves.
Team Dad: Light, "Mello, leave that poor kid alone and get in here, right now!"
That Poor Plant: L relates that he once managed to kill a cactus by forgetting to water it.
Unusually Uninteresting Sight: Sorry, but after having a Shinigami appear in your bedroom in the middle of the night a run-of-the-mill ghost isn't going to cut it...