I feel sorry for Conan, Ran, and Haibara. For Conan, while solving cases as a kid is tough enough, keeping secrets from the one you care for the most must be really hard to take in. It also must be really hard for him to see Ran heartbroken that Shinichi isn't around anymore.
I feel sorry for Ran because she hardly ever gets to see or spend time with her childhood friend Shinichi anymore, Even though she isn't aware that Conan is actually Shinichi. When she says that she's glad she gets to spend time with Conan because she reminds him of Shinichi, makes me feel sorry for her. She's been through a lot, but what I like about her is that she's very strong and never gives up.
For Haibara, is because the loss of her sister. That is very hard to take in. Also because she has to keep from being seen because the Black Organization are after her, so she's practically hidden from the public. She must be hurting inside, since she's been through a whole lot throughout the series.