If it’s normally drawing 2A, you’d want one that has a hold of 2A or even a little bit above. The region between hold and trip is basically an unknown state in which it may proceed to trip, or it may be fine. The trip current is where they know with high certainty, for a given ambient temperature (check the datasheet of the devices you’d be looking at!) that the package will not be able to dissipate the heat generated quickly enough and thus cause an escalation of the resistance.
One thing you may want to keep in mind as well is what you’re trying to protect your circuit from, and how critically so. Scouring Digikey for a component, Ihold at 2A gives me a minimum Itrip of 3.5A – but at that 3.5A, it’ll take quite a while for it to actually reach that trip ‘point’ (checked 2 manufacturers). You can see that in the datasheet for this fuse as well – “Time to trip” is stated as a maximum of 2.5 seconds at 1.25A in 20°C.. but if you look to the left, the ‘trip current’ at 20°C is said to be 0.5A – so it’ll take a fair bit longer. If that’s not acceptable for your use case, you may have to check alternatives.
