For example, what is the subject of the following sentence?
八時に来るようにしてください。
The speaker or the opponent?
For example, what is the subject of the following sentence?
八時に来るようにしてください。
The speaker or the opponent?
Hope I've understood you correctly:
くださる means 'to give'.
(You) give (me) the favour of making sure to come at 8 o'clock. = Please make sure to come at 8 o'clock
The person doing the giving (you) is the opponent which is the subject of くださる. The speaker (me) is the indirect object.