What determines the meaning of ‘rise’ with no adverb or preposition?

Question

From my earlier question, I got “rising” in the following citation means getting up from the bed.

1.(Harry was sitting up on a bed in the hospital wing at school, surrounded by his visitors. Fudge, one of them, started to insult Harry.)

"Insane," whispered Fudge, still backing away. "Mad ..."

And then there was silence. Madam Pomfrey was standing frozen at the foot of Harry's bed, her hands over her mouth. Mrs. Weasley was still standing over Harry, her hand on his shoulder to prevent him from rising. Bill, Ron, and Hermione were staring at Fudge. (Harry Potter and the Goblet of Fire (4) [US Version]: p.709)

Then I came across another rise, which obviously means getting angry.

2.(Malfoy provoked Harry and Ron.)(They are not sitting or kneeling.)

"Don't rise," Hermione whispered imploringly to Harry and Ron, who were both watching Malfoy, faces set and fists clenched. "It's what he wants…." (Harry Potter and the Order of the Phoenix (5) [US Version]: p.361)

No.1 means getting out from the bed and No.2 means getting angry or upset. That's okay, but I'd like to know why rise in No.1 meaning is so obvious. I'd appreciate it if you could clarify it for me.

Side Note:

Actually, I have a guess about what determines the meaning of rise and that's as follows; When the person who is told to rise has already been up on his feet, the rise means getting angry. On the other hand, when the person has been sitting or else, the rise means assuming a standing position or getting out from the bed.

There might not be such a rule. But in that case, I can’t figure out why rise in No.1 definitely means getting out from the bed, because Harry is insulted and anyone would get excited in the situation. It's not surprising Mrs. Weasley prevented him from getting excited. Besides, a dictionary says putting a hand on one’s shoulder sometimes expresses restraining someone's excitement. (eg. Jonathan was outraged. Fletcher, seeing his face, put a hand sharply on his shoulder and said, "Don't say anything you might regret…." )

Answer 1

The use of rise in the first example is literal. In the second, it’s figurative, and refers to the way in which fish rise to the bait.

Answer 2

In the second example, the verb "rise" gives me the feeling it means "don't rise to the occasion", ie don't do what boys do in cases like this one, when everyone expects them to fight when provoked. I don't know why it doesn't appear in its full form. Usually, the expression "rise to the occasion" is used to speak positively about meeting the demands of a situation. Since fighting is viewed as proof of masculinity and courage by boys (whereas girls have a different opinion), I'd say Hermione is asking them not to do what is expected of them at that given moment.