What is this 「も」?

Question

In Final Fantasy IV, a character says this line:

陛下にもお考えがあってのことだ。
"His Majesty must have his reasons [for sending you to steal the crystal]."

Contextually, it does not make sense for it to be "His Majesty must also have his reasons." or "Even His Majesty must have his reasons."

So, what exactly is the meaning of the も here? (大辞林 lists a 尊敬 usage of 「にも」, could that be what this is? Does that mean に alone would not show 尊敬?)

_Context:

_{「僕は、陛下の命令で暗黒剣を極めた。 でもそれはバロンを守る為で、罪もない人々から略奪をする為ではなかったはずだ。」
「そんなに自分を責めるな。 陛下にもお考えがあってのことだ。」
「カイン、お前が羨ましいよ。」}

Answer 1

That is not the [尊敬]{そんけい} usage of にも for at least three reasons.

1) 尊敬 (= "respect") is already expressed in the words [陛下]{へいか} and the お part of お[考]{かんが}え.

2) 「～～にも考えがある」 is a frequently-used set phrase in which the subject (the ~~ part) can be a first-person pronoun or even a murderer.

3) にも is used for 尊敬 only in highly limited situations, such as formal letters and speeches as with the example in 大辞林 that you linked to. It is not used for 尊敬 in a conversation that contains casual words like [僕]{ぼく} and お[前]{まえ} as in this case.

So, what is this も? I would have to say it is for "emphasis" but that does not mean that it means "even" or "also". As I always freely admit, English is my worst language but I still do not believe that there is a word that could express the nuance of this も in English.

We say 「～～にも考えがある」 when it appears that someone has an idea that is a little more profound or unexpected or even surprising than what others might tend to think it would be. It is this kind of subtle emphasis that も can often express, making it a killer for the learners.

Answer 2

It seems to be closest to 《接続助詞「に」＋係助詞「も」》, using 大辞泉's second meaning for も as a 係助詞:

② 他にも類似の事物が存在することを言外にほのめかす形で，ある事物を提示する。

To apply this definition here, I would say the も is emphasizing the otherness of His Majesty - intimating that it might not be the idea the speaker would have, but His Majesty has his own ideas.