Which of the four sons -mentioned in the Hagadah - asks this question?
Rashi (to 13:5): The Rasha; 1 who excludes himself from the Tzibur (by inserting the word "Lachem").
Yerushalmi Pesachim, 9:4: The Rasha asks this question, adding - 'Why do you bother us with all this (unnecessary) labor each year? 2
The Yerushalmi in Pesachim 9:4 - cited in the Hagadah ('k'Neged Arba'ah Banim') - lists the sources of all four sons. Refer also to 12:26:1.1:1 and note.
Yerushalmi (ibid.): Thereby excluding himself from the Avodah. And we answer him correspondingly, "Ba'avur Zeh Asah Hashem Li" (13:8) - For me He did it, and not for him; had he been there, he would never have gone out!' See Torah Temimah, note 201.
Why does the Torah write "Ki Yomeru Aleichem" in connection with the wicked son; and "Ki Yish'alecha Bincha" (Devarim 6:20) in connection with the wise son?
Oznayim la'Torah and Meshach Chochmah: Because whereas the wise son asks because he wants to know, the wicked son who thinks he knows better what is right and what is wrong, is making a statement (in a mocking tone). 1
'What use is this Mitzvah to you!' (as in Tehilim 8:5 [See Keli Yakar]). That is why we do not answer him directly, but rather in the form of a counter-statement ("va'Amartem... " (12:27)) explaining to ourselves the significance of the Korban Pesach, so as not to be influenced by his shameful attack on the Mitzvah. Refer also to 12:26:1:1*, and to 13:14:1.7:1.
What is bothering the wicked son?
Rashbam: The fact that this Yom-Tov is different from every other Yom-Tov in so many ways.
Seforno: He is bothered, a. by the fact that the Korban Pesach is brought on an ordinary weekday, unlike the other [special] Korbanos, and that it is brought after the afternoon Tamid (and not in between the two Temidim, like all other Korbanos are); b. because, since the Pesach is a form of communal Korban, why must each person bring his own? Why will one not suffice for the entire community?
Oznayim la'Torah: He doesn't mind the Matzah and the Maror (or eating a nice piece of lamb). On the contrary; he says, 'May there be many more days of celebration like that!' It's the Avodah that accompanies the Korban Pesach that bothers him.
"V'Hayah Ki Yomeru... " implies news. What news is the Torah conveying here?
Mechilta #1: The Torah is conveying bad news - that Torah will be forgotten from Yisrael. 1
Mechilta #2: The Torah is conveying the good news - that they are destined to have children and grandchildren 2 (albeit wicked ones).
See Torah Temimah, note 200. According to this explanation, the Pasuk is not speaking about a wicked son. Refer to 12:27:0.3:1.
Rashi (to 13:5) writes that the wicked son asks this question, since he said "Lachem." But later, Rashi (to 13:14) explains that the Chacham asks about the Mitzvos that Hashem commanded - even though he also says "Eschem" (Devarim 6:20)?
Moshav Zekenim: Because the Chacham also said "Elokeinu," to include himself.
Da'as Zekenim, Hadar Zekenim, and Rosh (all to Devarim 6:20): The Chacham only says 'Eschem' because he was not yet born when Hashem commanded them.
Maharal: Refer to 13:8:2.2:1.